«< 


LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 


Class     ^  I ! 


ESSENTIALS  OF 

MILK   HYGIENE 

A  PRACTICAL    TREATISE   ON    DAIRY   AND    MILK 
INSPECTION    AND    ON   THE   HYGIENIC    PRODUC- 
TION AND  HANDLING  OF  MILK,  FOR  STUDENTS 
OF  DAIRYING  AND   SANITARIANS 


BY 

C.   O.    JENSEN 

Professor  in  the  Royal  Veterinary  and  Agricultural  College  of  Copenhagen,  Denmark. 


TRANSLATED    AND    AMPLIFIED 


BY 


LEONARD   PEARSON 

Dean  of  the  Veterinary  Faculty  of  the  University  of  Pennsylvania,  State  Veterinarian 

of  Pennsylvania,  Member  of  the  Advisory  Board  of  the  State  Department 

of  Health,  and  Member  of  the  Board  of  Health  of  Philadelphia. 


ILLUSTRATED 


OF  THE 

I    UNIVERSITY  ] 

OF 


PHILADELPHIA    AND    LONDON 
J.   B.    LIPPINCOTT    COMPANY 


-'3MI 


COPYKIGHT,   1907 
BY 

J.  B.  LIPPINCOTT  COMPANY 


Published  June,  1907 


Electrotyped  and  printed  by  J.  B.  Lippincott  Company 
The  Washington  Square  Press,  Philadelphia,  U.  S.  A. 


CONTENTS. 


PAGE 

AUTHOR'S  PREFACE  (TO  THE  ENGLISH  EDITION) v 

TRANSLATOR'S  PREFACE   vii 

INTRODUCTION    9 

MILK  AND  ITS  COMPOSITION 12 

HARMFUL  PROPERTIES 60 

PASTEURIZATION  AND  STERILIZATION   128 

THE  USE  OF  MILK  FOR  INFANTS 147 

PUBLIC  CONTROL  OF  THE  PRODUCTION  AND  HANDLING  OF  MILK 157 

APPENDIX  I.     THE  MILK  SUPPLY  OF  COPENHAGEN 239 

APPENDIX  II.     GERMAN  INSTRUCTIONS  FOR  PRODUCING  NURSERY 

MILK    249 

APPENDIX  III.     THE  MILK  COMMISSION  OF  PHILADELPHIA 251 

APPENDIX  IV.     A  SCORE  CARD  FOR  DAIRY  FARMS 257 

APPENDIX  V.     THE    MILK    COMMISSION    OF    ESSEX    Co.,    NEW 

JERSEY 259 

APPENDIX  VI.     REPORT  OF  THE  ROYAL  COMMISSION  ON  TUBER- 
CULOSIS      269 

INDEX  .   271 


161755 


AUTHOR'S    PREFACE, 

(TO    THE     ENGLISH    EDITION.) 


IN  the  hygienic  movement  of  the  times  the  control  of 
the  production  and  handling  of  milk  has  not  been  given 
a  prominent  place.  But  the  significance  of  this  subject 
is  now  plain  and  everywhere  efforts  are  being  made  to 
institute  such  a  control  or  to  improve  it.  The  efforts  of 
cities  to  secure  a  wholesome  supply  of  milk  must  of 
course  differ  and  be  adapted  to  local  conditions,  but 
they  must  all  be  governed  by  the  same  principles  and 
rest  on  exact  knowledge  of  the  composition  of  milk  and 
of  the  dangers  that  are  to  be  avoided. 

In  the  preparation  of  this  book  it  has  been  my  hope 
that  it  would  not  only  be  of  use  to  my  Danish  col- 
leagues, but  that  my  colleagues  in  other  countries  would 
find  it  to  be  of  service  to  them.  For  this  reason  I  pub- 
lished a  Danish  and  a  German  edition  simultaneously 
and  for  the  same  reason  I  have  been  very  glad  to  grant 
Prof.  Pearson's  request  for  permission  to  prepare  an 
English  edition. 

C.   0.  JENSEN. 


TRANSLATOR'S    PREFACE. 


THE  production  of  market  milk  is  a  rapidly  growing 
industry.  The  demand  for  milk  in  cities  is  continually 
increasing  and  there  is  reason  to  believe  that  the  rate 
of  increase  will  advance. 

The  milch  cow  transmutes  the  pasturage  and  forage 
of  the  farm  into  edible  protein,  lactose  and  fat — into 
units  of  nutriment  for  man — at  less  than  one-half  the 
cost  of  similar  units  in  beef  produced  by  the  steer. 
Milk  is  not  only  the  most  economical  but,  when  pure  and 
undefiled,  it  is  among  the  most  wholesome  and  it  is 
the  most  easily  digestible  of  all  foods  of  animal  origin. 
These  are  the  strongest  possible  reasons  for  its  extended 
use. 

On  the  other  hand,  there  is  no  other  food  that,  under 
ordinary  conditions,  is  so  exposed  to  contamination, 
that  is  so  easily  contaminated  or  that  so  fosters  contami- 
nation as  milk.  Hence  the  necessity  for  the  study  of 
milk  hygiene. 

The  subject  is  a  broad  one.  Milk  hygiene  involves 
some  knowledge  of  the  physiology  of  cows,  especially 
with  relation  to  breeding,  lactation  and  nutrition;  of 
comparative  pathology,  particularly  the  various  dis- 
eases of  the  udder  of  the  cow,  the  abnormal  conditions 
that  affect  milk  secretion,  and  the  infectious  diseases 
of  cattle  and  of  man  that  may  be  transmitted  by  milk; 
of  bacteriology,  in  regard  to  the  pathogenic  organisms 
and  the  saprophytes  that  occur  in  milk,  their  effects, 
their  behavior  under  various  conditions  and  especially 
at  different  temperatures ;  of  the  chemistry  of  milk  and 

its  adulterations  and,  besides  these,  there  must  be  added 

vii 


TRANSLATOR'S  PREFACE 

certain,  important    chapters    from    animal   husbandry, 
dairy  husbandry  and  dairy  industry. 

Until  quite  recently,  milk  inspection  in  the  United 
States  has  been  carried  on  by  untrained  men  who  have 
had  little,  if  any,  knowledge  of  the  sources  or  nature  of 
the  contaminations  of  milk  or  of  the  means  by  which 
they  must  be  avoided ;  their  whole  technical  equipment 
has  consisted  in  a  few  rule-of-thumb  tests  to  detect 
gross  adulterations.  A  large  number  of  milk  inspection 
services  are  still  organized  on  this  basis.  In  several 
cities,  however,  attention  has  been  paid  to  microscopic 
and  bacteriologic  examinations  of  milk,  and  it  has  been 
shown  that  a  very  large  proportion  of  the  supply  fails  to 
meet  even  a  moderate  standard  for  cleanliness,  thus  re- 
vealing the  need  for  measures  at  the  seat  of  production 
and  during  transit  to  prevent  injurious  contaminations. 

It  is  becoming  increasingly  manifest  to  sanitarians 
that  more  must  be  done  to  protect  consumers  from  the 
unwholesome  conditions  and  the  diseases  propagated 
and  transmitted  by  milk  and  the  broader  men  in  dairy 
industry  realize  that  milk  must  be  made  safe  and  be  pro- 
tected if  it  is  to  find  and  retain  its  proper  place  in  the 
dietary  of  the  people. 

This  makes  a  demand  for  a  discussion  of  milk 
hygiene  from  the  standpoint  of  the  sanitary  supervision 
of  market  milk — from  the  side  of  the  man  who  is  to  do 
the  practical  work  of  protecting  the  milk  supply — and  it 
is  this  demand  that  Professor  Jensen's  book  is  planned 
to  meet. 

LEONARD  PEARSON. 


PART    I. 


INTRODUCTION. 

Cow's  milk  has  a  peculiar  place  among  our  food 
stuffs  in  that  it  is  not  only  an  important  and  indispens- 
able part  of  the  daily  dietary  of  most  people,  but  it  is 
being  used  more  and  more  for  the  feeding  of  infants  and, 
indeed,  is  often  almost  the  exclusive  food  for  children 
during  the  first  years  of  life.  It  is,  therefore,  quite  natu- 
ral that  at  present  when  the  science  of  hygiene  is  receiv- 
ing so  much  attention — especially  in  relation  to  the  large 
cities — that  there  should  be  a  demand  for  a  reliable 
supervision  of  market  milk.  It  is  true  that  the  milk 
trade  in  cities  has  been  subject  to  a  certain  inspection, 
but  attention  has  been  directed  to  only  one  side  of  the 
question,  to  the  possibility  of  adulteration,  and  to  pro- 
vide that  fat  is  not  removed  and  that  there  is  no 
alteration  in  the  composition  of  the  milk.  From  the 
standpoint  of  hygiene  this  is  merely  of  secondary  im- 
portance because  it  is  in  other  ways  that  milk  acquires 
dangerous  properties  and  may,  indeed,  become  the 
means  of  spreading  virulent  diseases. 

A  properly  organized  milk  control  of  the  present 
day  can  not,  therefore,  be  restricted  to  determining 
that  milk  offered  for  sale  is  unadulterated.  On  the 
contrary,  it  must  be  its  chief  purpose  to  prevent  milk 
possessing  injurious  properties  from  coming  into  the 
market  and  to  prevent  market  milk  from  acquiring  such 
properties  during  the  time  that  it  is  being  handled  and 
stored.  Since  it  is  possible  only  by  means  of  a  thor- 
ough, tedious  examination  to  determine  whether  a  given 

9 


10  MILK  HYGIENE 

sample  of  milk  is  unwholesome,  milk  control  can  not  be 
restricted  to  a  simple  inspection  of  the  milk  or  to  taking 
a  sample  for  further  examination.  To  insure  real 
safety,  the  inspection  must  be  broadened  to  cover  the 
health  and  feeding  of  the  cattle,  the  cleanliness  of  the 
producing  plant,  the  method  of  handling  and  caring  for 
the  milk  and  the  condition  of  health  of  the  people  who 
come  in  contact  with  it.  Milk  control  is,  for  the  reason 
stated,  more  difficult  and  more  expensive  than,  for 
example,  meat  inspection,  and  this  is  undoubtedly  one 
of  the  principal  reasons  why  the  control  of  milk  produc- 
tion and  the  milk  trade  is  so  defective  in  most  countries. 

During  recent  years,  a  somewhat  comprehensive  con- 
trol of  the  milk  trade  in  its  various  relations  has  been 
carried  out  in  a  number  of  large  cities,  but  a  thoroughly 
satisfactory  system  does  not  exist  and  will  be  difficult 
to  establish  on  account  of  its  cost.  In  Denmark,  a 
long  step  has  been  taken  in  the  matter  of  milk  control 
through  the  voluntary  initiative  of  a  single  large  com- 
pany which,  at  a  time  when  milk  hygiene  was  receiving 
little  attention,  inaugurated  a  very  comprehensive 
system  of  control,  and  thereby  set  an  example  that  has 
been  followed  by  other  large  companies,  not  only  in 
Copenhagen  but  also  in  foreign  countries.  These  com- 
panies have,  in  some  respects,  carried  their  control  to 
a  point  far  beyond  that  contemplated  at  the  time  by 
the  public  authorities. 

Copenhagen  is  on  the  point  of  supplementing  its 
health  laws  in  relation  to  the  milk  trade  within  its 
limits. 

As  it  is  chiefly  through  the  work  of  Veterinarians 
that  meat  inspection  has  gradually  increased  and  is  now 
conducted  in  a  scientific  manner,  so,  to  a  large  extent, 
we  have  to  thank  the  Veterinarians  for  the  fact  that 
the  control  of  the  production  and  sale  of  milk  is  grow- 


INTRODUCTION  11 

ing  steadily.  Not  only  is  important  scientific  work 
being  carried  on  by  them  in  several  directions,  which 
supplements  the  work  of  chemists  and  physicians,  but 
the  necessity  for  milk  control  is  constantly  being  pointed 
out  in  meetings  of  veterinarians,  in  the  International 
Veterinary  Congresses  and  in  the  Congresses  for 
Hygiene.  A  special  journal  is  devoted  to  questions 
pertaining  to  milk  hygiene,  in  conjunction  with  meat 
inspection,  and  separate  courses  in  milk  hygiene  are 
given  in  many  Veterinary  Colleges. 

What  follows  is  essentially  the  substance  of  lectures 
given  by  the  author  in  the  Veterinary  and  Agricultural 
College  of  Copenhagen.  On  some  points  in  the  prepara- 
tion of  the  book,  the  lecture  notes  have  been  expanded ; 
for  example,  in  citing  the  instances  of  disease  resulting 
from  milk  possessing  injurious  properties.  Since  vet- 
erinarians are  frequently  consulted,  by  sanitary  officers 
and  by  dairymen,  in  regard  to  the  adulteration  of  milk, 
it  is  considered  to  be  desirable  to  discuss  rather  thor- 
oughly the  composition  of  milk,  the  variations  that  occur 
under  different  conditions,  and  the  adulterations.  It  is 
also  considered  to  be  appropriate  to  briefly  treat  upon 
the  use  of  milk  as  food  for  infants. 

DIVISION  OF  SUBJECT 

The  subject  matter  of  this  book  is  divided  into  the 
following  parts: 

Milk  and  its  composition. 

Injurious  properties  that  milk  may  possess. 

Pasteurization  and  sterilization  of  milk. 

The  use  of  milk  for  infants. 

In  order  to  prevent  the  expansion  of  the  book  to 
unnecessary  proportions,  the  hygiene  of  other  dairy 
products  as  cheese  and  butter,  and  milk  preparations 
as  condensed  milk,  milk  powder,  etc.,  is  not  discussed. 


PART   II. 

MILK  AND  ITS  COMPOSITION. 


I.   THE  MILK  GLANDS  AND  MILK  SECRETION. 

THE  tissue  of  the  milk  glands  is  shown  by  macro- 
scopic examination  (Fig.  1)  to  be  composed  of  small 
lobules  separated  by  bands  of  connective  tissue  in  which 
lie  the  larger  blood  vessels,  the  nerves  and  the  excretory 
ducts  and  in  which  there  is  sometimes  a  considerable 
quantity  of  fat  tissue.  The  gland  tissue  itself  is  com- 
posed of  complexly  branching  glandular  tubes  which, 
during  the  period  of  lactation,  are  provided  with 
numerous  globular  distensions,  so  that  the  type  of  the 
milk  gland  is  intermediate  between  that  of  the  alveolar 
and  tubular  types.  The  glandular  pockets  are  provided 
with  a  membrana  propria  (Fig.  2)  and  are  lined  with 
epithelial  cells.  In  young  and  farrow  animals,  the  cells 
are  thin  and  square  or  high  and  narrow,  and  resemble 
superficial  epithelium.  During  the  period  of  lactation 
these  cells  become  large  and  tense.  This  epithelium  is 
usually  composed  of  but  a  single  layer,  although,  in  old 
cows,  it  is  sometimes  found  to  be  composed  of  several 
layers. 

Toward  the  end  of  gestation,  the  secretory  function 
of  the  udder  begins  with  the  production  of  colostrum  or 
the  so-called  "beast  milk."  This  is  a  thick,  reddish  or 
yellowish  fluid  with  a  taste  more  salty  than  that  of  nor- 
mal milk,  and  under  the  microscope  (Fig.  3)  it  is  seen 
that  it  contains  numerous  free  fat  globules  and  a  large 
number  of  round  or  mulberry  shaped  cells — the  so-called 
colostrum  bodies — that  are  filled  with  fat  globules. 
12 


FIG.  i. 


Section  of  udder  tissue  of  a  cow.    Low  magnification.    One  entire  lobule  is  shown  and 
parts  of  five  others.    Microphotograph. 


FIG.  2. 


S7  £*~X*V/V  ft.    \' 

.&&*•*£  W,a      *^ 

r/     '^AJ-.l. 


X 


,*£f 


Section  of  tlio  udder  tissue  of  a  cow.  High  magnification.  Shows  individual  glandular 
pockets  with  their  endothelial  lining  and  the  connective-tissue  framework.  Micro- 
photograph. 


FIG.  3. 


Colostrum.— The  udder  secretion  of  a  cow  that  has  recently  calved.  Stained  light/ly  with 
osmicacid,  causing  the  fat  globules  to  become  dark.  Shows  several  colostrum  bodies 
and  fat  globules.  Microphotograph. 


FIG.  4. 


Milk.-  The  fat  globules  are  shown  as  light  circles  on  a  -dark  background.     Micro 
photograph. 


I    UNIVERSITY 

V 


THE  MILK  GLANDS 


Some  cells  are  seen  that  have  a  distinct  amoeboid 
movement;  these  are  leucocytes  that  have  wandered 
through  the  epithelium  into  the  glandular  pockets  and 
have  taken  up  some  globules  of  fat.  Besides  these, 
there  are  to  be  found  some  epithelial  cells  that  have 
undergone  more  or  less  degeneration. 

The  chemical  examination  of  colostrum  shows  its 
principal  constituents  to  be:  water,  proteids  (especially 
globulin  and  albumin,  and  also  casein  and  nuclein  com- 
pounds), sugar,  fats  and  cholesterin,  and,  besides  these, 
lecithin,  various  salts  and  other  substances  in  smaller 
quantities.  Colostrum  differs  from  normal  milk  in  its 
higher  percentage  of  solids  and  especially  in  its  higher 
content  of  globulin,  albumin,  nuclein  compounds  and 
lecithin.  The  chemical  composition  of  colostrum  differs 
slightly  among  animals  of  different  species.  In  the 
course  of  a  few  days,  the  secretion  of  colostrum  passes 
into  milk  secretion  so  that  at  the  expiration  of  about 
one  week,  the  secretion  possesses  the  characteristic  ap- 
pearance and  composition  of  milk. 

The  microscopic  picture  of  milk  is  quite  different 
from  that  described  above.  A  very  large  number  of 
fat  droplets  (milk  globules,  Fig.  4)  of  varying  sizes,  and 
a  small  number  of  more  or  less  degenerated  cells  (colos- 
trum bodies,  gland  cells)  are  distributed  uniformly  in 
a  transparent  fluid,  the  milk  plasma. 

It  was  formerly  thought  that  milk  secretion  differed 
in  important  particulars  from  other  secretions  in  that, 
it  was  considered,  it  occurred  through  partial  destruc- 
tion of  the  gland  cells.  It  was  supposed  that  during 
secretion  the  cells  became  longer  and  swollen,  that  the 
nucleus  receded  to  the  base  of  the  cell  while  the  part 
pointing  toward  the  cavity  of  the  alveolus  became  filled 
with  numerous  small  fat  globules.  It  was  thought  that 
after  this  "  fatty  degeneration  "  reached  a  certain 


14  MILK  HYGIENE 

stage,  there  was  a  pouring  out  and  solution  of  this 
part  of  the  cell,  that  the  fat  globules  were  transformed 
into  milk  globules  and  the  albuminous  part  of  the  cell 
protoplasm  became  part  of  the  milk  fluid  and  that  the 
remaining  portion  of  the  cell,  with  the  nucleus,  was  soon 
regenerated,  whereupon  a  fatty  degeneration  again  oc- 
curred in  the  regenerated  portion  of  the  cell.  Recently, 
doubts  have  arisen  as  to  whether,  during  the  production 
of  milk,  there  is,  after  all,  a  material  disintegration  of 
the  cell  protoplasm.  Ottolenghis  's  investigations  appear 
to  show  clearly  that  milk  secretion  is  an  active  cell 
process  precisely  as  other  secretions  are,  and  that  it 
does  not  depend  upon  the  destruction  of  the  cell.  The 
destruction  of  entire  cells  and  their  elimination  appears 
to  occur  only  to  a  limited  degree,  but  the  presence  of 
karyokinetic  figures  shows  that,  here  and  there,  in  the 
gland,  such  a  disintegration  does  occur  with  consequent 
reproduction. 

The  milk  from  animals  of  different  species  contains 
the  same  ingredients,  namely:  water,  albuminoids  (es- 
pecially casein  and  albumin),  milk  sugar  (lactose),  fats 
and  inorganic  salts.  In  regard  to  quantitative  compo- 
sition, there  are  marked  differences  between  the  milks 
of  animals  of  different  species. 

Among  the  ingredients  of  milk  it  is  supposed  that 
casein  is  the  direct  product  of  the  gland  tissue,  globulin 
of  the  broken  down  parts  of  cells,  while  it  is  not  known 
whether  albumin  originates  at  the  same  source  or  comes 
from  the  blood.  Concerning  the  origin  of  lactose,  there 
are  different  opinions.  Some  investigators  suppose  this 
material  is  formed  in  the  liver  from  glycogen  or  related 
materials,  while  others  think,  and  indeed  with  reason, 
that  it  is  formed  in  the  udder  by  synthetic  building  up 
of  glucose  and  galactose.  The  latter  cannot,  as  such, 
have  been  taken  up  with  the  food,  but  must  have  been 


THE  CONSTITUENTS  OF  MILK  15 

formed  in  the  body  by  a  breaking  down  of  the  galac- 
tins  of  the  food.  Others  regard  lactose  as  a  product 
of  certain  proteids  (glycoproteids).  Milk  fat  is  de- 
rived partly  from  the  fat  in  the  food,  partly  from  the 
fat  tissues  of  the  animal;  but  these  fats  undergo  a 
material  transformation  in  the  tissues  of  the  udder, 
so  that  certain  easily  recognizable  fats,  even  when  taken 
up  in  quantity  with  the  food,  are  either  not  visible  at  all 
in  the  milk  or  appear  in  very  small  quantity  or  are 
merely  transitory.  Doubtless,  milk  fat — just  as  fat  tis- 
sue— may  also  be  derived  from  the  carbohydrates  of  the 
food.  Among  the  other  ingredients  of  milk,  citric 
acid  does  not  originate  in  the  food,  but  results  from 
metabolism. 

Milk  secretion,  to  a  great  degree,  bears  the  impres- 
sion of  specific  action  of  the  cells  which,  however,  may 
be  influenced  by  external  circumstances,  but  usually  only 
temporarily.  This  is  naturally  of  great  importance  for 
the  young  animal,  which  is  nourished  entirely  or  chiefly 
on  its  mother's  milk,  as  frequent  and  sudden  changes 
in  the  composition  of  the  milk  would  be  harmful,  if  not 
dangerous. 

Milk  secretion,  it  appears,  may  be  checked  through 
the  influence  of  the  central  nervous  system,  but  is  regu- 
lated through  the  sympathetic  nerve  centres.  In  this 
connection,  observations  agree  that  certain  irritant 
drugs  (as  pilocarpine)  and  other  influences  that  decid- 
edly affect  the  secretory  function  of  other  glands,  influ- 
ence milk  secretion  very  little  if  at  all;  furthermore, 
section  of  the  nerve  trunks  of  the  udder  does  not  disturb 
secretion. 

II.    THE  CONSTITUENTS  OF  MILK 

As  already  mentioned,  milk  of  different  mammals 
consists  essentially  of  the  same  materials,  namely: 
water,  protein,  sugar,  fats  and  inorganic  matter;  but 


16  MILK  HYGIENE 

great  differences  are  shown  by  quantitative  analyses  of 
the  milk  of  the  different  species. 

Water.  The  quantity  of  water  usually  amounts  to 
80  to  90  per  cent,  of  the  weight  of  the  milk ;  under  certain 
circumstances  and  with  some  animals  it  is  even  consider- 
ably less.  With  the  whale,  the  quantity  of  water  is 
scarcely  50  per  cent. 

Proteids.  Of  proteids,  the  three  following  are  always 
found :  casein,  lact  albumin  and  lacto globulin.  A  kind  of 
albumose-like  compound  is  sometimes  found  in  insignifi- 
cant quantity — the  so-called  animal  gum — which  is  also 
found  in  certain  tissue  and  in  the  saliva,  and  probably 
comes  from  the  breaking  down  of  glycoproteids  (mucin, 
etc.).  Moreover,  other  proteids  are  often  described  as 
normal  constituents  of  milk  (albumins,  albumoses,  meat 
acids,  etc.),  but  it  is  safe  to  conclude  that  these  do  not 
occur  in  fresh  milk,  while  such  compounds  are  readily 
formed  by  bacteria  and  ferments  and  can  be  formed  by 
chemical  means. 

Casein  is  a  nucleo-albumin  and,  as  such,  it  contains 
phosphorus.  It  is  insoluble  in  water,  but,  by  virtue  of 
its  property  as  an  acid,  it  forms  soluble  salts  with  alka- 
lies. There  are  two  series  of  casein  salts,  basic  and 
neutral ;  the  solutions  of  the  latter  have  a  milky  appear- 
ance. Casein  is  found  dissolved  in  milk  in  the  form  of 
a  neutral  lime  salt,  which  aids  in  giving  to  milk  its 
white,  opaque  appearance.  When  boiled,  a  solution  of 
casein  is  overcast  with  a  thin  membrane  of  coagulated 
casein;  but  a  real  coagulation,  as  it  occurs  in  albumins 
and  globulins,  does  not  take  place.  When  the  fluid  has 
reached  a  certain  degree  of  acidity  casein  coagulates  at 
75°  C.  and  the  precipitated  casein  is  not  again  soluble. 
After  the  addition  of  diluted  mineral  acids  or  of  acetic 
acid,  casein  is  precipitated  as  flakes  or  lumps,  but  under- 
goes no  chemical  change  and  is  again  easily  soluble  in 


THE  CONSTITUENTS  OF  MILK  17 

lime  water  and  diluted  alkalies.  The  separation  depends 
only  and  solely  upon  the  breaking  down  of  the  casein 
calcium  compound.  By  rennet  (chymosin,  etc.)  casein 
is  precipitated  as  flakes  (human  milk  and  donkey  milk), 
or  as  a  firm  gelatinous  mass  (e.g.  cow's  milk).  The  dif- 
ferent modes  of  precipitation  do  not  appear  to  come 
from  the  differences  in  the  casein,  but  are  due  to  the  dif- 
ferent salt  content  of  the  different  kinds  of  milk.  Under 
the  influence  of  chymosin,  casein  is  transformed  into 
paracasein,  which  in  its  compound  with  lime  is  insoluble 
in  water  and,  therefore,  may  be  precipitated  in  this  way. 

The  action  of  the  rennet  ferments  is  quite  different 
from  the  precipitation  of  casein  by  acids.  tWith  the  pre- 
cipitation of  paracasein,  an  albumose-like  proteid  re- 
mains in  solution  (whey  proteid),  so  the  action  of  the 
rennet  ferment  is  to  split  the  casein.  By  the  growth 
of  bacteria  in  milk,  the  casein  is  often  thrown  out  of 
solution,  either  as  a  result  of  the  formation  of  acids 
or  by  the  chymosin-like  effect  of  ferments  produced  by 
bacteria.  Sometimes  the  separation  occurs  from  the 
joint  action  of  the  ferments  and  the  acids  that  are 
formed.  In  pepsin  digestion,  casein  is  dissolved  with  the 
formation  of  albumoses  (caseoses)  and  paranuclein, 
which  is  rich  in  phosphorus.  In  the  organism,  para- 
nuclein is  dissolved  by  the  pancreatic  juice,  is  absorbed, 
and  is  excreted  with  the  urine  as  phosphoric  acid. 

It  has  often  been  said  that  casein,  as  it  is  found  in 
the  milk  of  different  animals,  is  not  the  same  and,  as 
evidence  of  this,  reference  has,  incorrectly,  been  made 
to  the  different  ways  in  which  casein  separates  from 
milks  acted  upon  by  rennet.  A  more  important  indica- 
tion, although  the  observation  requires  confirmation,  is 
in  the  claim  that  in  the  pepsin  digestion  of  human  milk 
no  paranuclein  is  formed.  According  to  Hammarsten's 
thorough  work,  casein  appears  to  show  no  chemical  dif- 


18  MILK  HYGIENE 

ference  in  different  kinds  of  milk.  The  latest  investiga- 
tions concerning  the  powers  of  the  organism  to  form 
specific  anti-albumins  (precipitins)  following  the  injec- 
tion of  albumin  solutions,  prove,  however,  that  the 
casein  of  different  species  of  animals  has  certain  dif- 
ferences, even  though  these  are  so  slight  that  they  can- 
not be  detected  chemically. 

The  lactalbumin  is  very  similar  to  the  albumin  of  the 
blood,  but  it  appears  to  differ  from  this  in  some  particu- 
lars. It  coagulates  at  about  70°  C.,  and,  like  all  other 
albumins,  it  is  not  precipitated  in  a  neutral  solution 
of  sodium  chloride  and  magnesium  sulphate,  but  it  is 
precipitated  in  a  saturated  solution  of  ammonium 
sulphate. 

The  lacto globulin  occurs  in  milk  in  very  small  quan- 
tity, merely  in  traces,  while  colostrum  is  comparatively 
rich  in  this  substance.  It  coagulates  at  75°  C. ;  it  is  pre- 
cipitated in  the  same  way  as  serum  globulin  and,  like 
serum  globulin,  is  insoluble  in  water,  but  is  soluble  to 
some  extent  in  weak  salt  solution. 

Carbohydrates.  Of  the  carbohydrates,  lactose,  or  milk 
sugar,  occurs  as  a  constant  constituent  in  the  milk  of 
the  cow  and  of  most  other  mammals.  Some  investiga- 
tors claim  that  in  colostrum  there  is  a  monohexose, 
which  is  probably  glucose,  and  it  is  not  unlikely  that  in 
the  milk  of  certain  animals  other  kinds  of  sugar  appear ; 
for  example,  it  is  cited  that  a  peculiar  kind  of  sugar, 
tewficose,  is  found  in  considerable  quantity  in  the  milk 
of  the  Egyptian  buffalo. 

Lactose  (C^EL^On  +  H20)  is  a  disaccharid  which 
is  split  by  hydrolysis  (e.g.  by  means  of  heating  with 
dilute  acids,  action  of  ferments)  into  glucose  (grape 
sugar)  and  galactose  as  follows: 

C12H22On  +  H2O  ==--  C6H12O6   f   C6H12O6 
Lactose  Glucose  Galaotose 


THE  CONSTITUENTS  OF  MILK  19 

Lactose  has  been  found  only  in  milk  and  must  be 
formed  in  the  organism;  but  this  formation,  as  has 
already  been  stated,  is  not  yet  thoroughly  understood. 
Commercial  lactose  is  derived  from  whey  as  hard  rhom- 
bic crystals  which  have  a  slightly  sweet  taste  and  are 
soluble  in  six  parts  of  cold  water.  By  the  action  of 
micro-organisms,  lactose  may  ferment  in  different  ways. 
Certain  yeasts  and  bacteria  cause  an  alcoholic  fermen- 
tation, while  other  bacteria  split  lactose,  forming  lactic 
acid  (causing  "  souring  "  of  milk)  and  several  other 
substances  as  by-products  (C02,  H,  formic  acid,  butyric 
acid,  etc.) ;  still  other  bacteria  form  as  their  chief  pro- 
duct, butylalcohol,  succinic  acid  or  acetic  acid.  Certain 
moulds  are  able  to  form  oxalic  acid  from  lactose  by  oxi- 
dation. Lactose,  like  glucose,  reduces  Fehling's  solution 
when  heated. 

Fats  are  found  in  the  milk  as  small  droplets  or  glob- 
ules, which  accumulate  upon  standing  into  a  layer  of 
cream,  and  which  are  easily  separated  from  the  other 
constituents  of  milk  by  means  of  centrifugal  force. 
Upon  shaking  milk  or  cream,  the  globules  of  fat  grad- 
ually coalesce  into  larger  drops  and  lumps  (butter).  It 
was  formerly  thought  that  the  fat  globules  were  sur- 
rounded by  a  membrane,  but  now  it  is  generally  believed 
that  it  is  not  so.  However,  under  the  microscope  one 
can  see  a  border  on  certain  individual  fat  globules, 
which  is  to  be  regarded  as  a  remainder  of  broken-down 
cell  protoplasm. 

Milk  fat  consists  of  a  mixture  of  different  fats,  the 
principal  of  which  are  olein,  palmitin  and  stearin, 
which  are  the  neutral  triglycerides  of  the  correspond- 
ing fatty  acids.  Besides  these  are  found  the  triglycer- 
ides of  myristic  acid  and  of  butyric  and  capronic  acids 
(the  last  two  volatile)  and  also  traces  of  triglyceride  of 
other  fatty  acids  (caprylic,  caprinic,  laurinic  and  arach- 


20  MILK  HYGIENE 

inic).  The  composition  of  the  fat  is  subject  to  numerous 
variations  and  these  are  not  alone  racial  peculiarities, 
for  individual  traits,  the  composition  of  the  food  and 
external  conditions  of  life  not  infrequently  influence  it. 

Other  Substances.  Milk  contains  other  substances 
in  very  slight  quantities :  urea,  kreatin,  kreatinin,  leci- 
thin, cholesterin  and  citric  acid.  It  is  not  yet  known  if 
these  appear  in  the  milk  of  all  animals  or  whether  some 
of  the  substances  are  characteristic  of  certain  animals 
only. 

Besides  these  substances,  milk  contains  some  inor- 
ganic salts  in  solution,  which  remain  after  evaporating 
and  burning  the  milk.  The  ash  consists  of  lime,  potash, 
sodium,  small  quantities  of  magnesia  and  traces  of  oxide 
of  iron  in  combination  with  phosphoric  acid,  chlorine 
and  sulphuric  acid.  The  small  surplus  of  basic  sub- 
stances in  the  ash  were  in  combination  with  citric  acid 
and,  perhaps,  with  other  organic  acids.  Phosphoric  acid 
and  lime  exist  partly  as  soluble  compounds,  partly  in 
combination  with  casein.  A  little  di-  and  tri-calcium 
phosphate  are  held  in  solution  by  the  action  of  the  casein 
and  are  therefore  precipitated  with  it.  The  milk  of  dif- 
ferent species  and  sometimes  of  different  individuals, 
shows  a  quantitative  difference  in  the  ash. 

According  to  recent  investigations,  milk,  at  least 
cow's  milk,  always  contains  a  ferment,  the  so-called 
galactase  (Babcock,  Russell),  which  is  capable  of  slowly 
peptonizing  protein.  The  significance  of  this  ferment 
and  its  composition  are  wholly  unknown  to  us ;  possibly 
it  comes  from  the  breaking  down  of  the  leucocyte 
(Barthel). 

Certain  gases  occur  in  the  free  state  in  milk. 
Investigations  on  this  subject  have  given  varying  re- 
sults, in  that  some  investigators  have  found  distinct 
quantities  of  oxygen  in  milk  just  drawn,  others  have 


THE  COMPOSITION  OF  MILK  21 

detected  only  a  trace,  or  none  at  all;  moreover,  milk 
always  contains  considerable  carbonic  acid  and  a  slight 
quantity  of  nitrogen.  Upon  standing,  this  relation 
changes,  for  carbonic  acid  escapes  and  oxygen  is 
absorbed.1 

III.    THE  COMPOSITION  OF  MILK  OF  DIFFERENT 
SPECIES   OF   ANIMALS 

It  has  been  stated  that  the  milks  of  different  species 
of  animals  consist  of  essentially  the  same  materials,  but 
that  in  their  quantitative  composition  they  show  quite  a 
little  difference.  As  will  be  considered  in  detail  later, 
there  are  great  variations  with  individual  animals  and, 
therefore,  the  figures  given  are  to  be  regarded  as  aver- 
ages and  they  are  to  be  accepted  with  some  reserve,  for 
not  all  are  the  result  of  a  sufficiently  great  number  of 
analyses;  still,  they  give  quite  a  good  picture  of  the 
striking  peculiarities  of  the  different  kinds  of  milk. 

Cow's  milk  is  white,  opaque,  has  a  slightly  sweetish 
taste  and  a  very  slight  odor.  It  shows  amphoteric  reac- 
tion to  litmus  paper,  e.g.,  it  colors  red  litmus  paper  blu- 
ish and  blue  reddish.  To  other  indicators,  milk  some- 
times shows  itself  to  be  acid,  sometimes  alkaline.  Ac- 
cording to  Courant,  it  can  be  demonstrated  that  100  c.c. 
of  fresh  cow's  milk  shows  the  same  amount  of  alkalinity 
toward  blue  litmus  as  41  c.c.  of  a  one-tenth  normal  solu- 
tion of  sodium  hydrate  and  the  amount  of  acidity,  as 
measured  by  phenolphthalein,  is  equivalent  to  that  of 
19.5  c.c.  of  a  one-tenth  normal  solution  of  sulphuric 
acid.  However,  milk  does  not  always  react  the  same, 
it  changes  especially  during  the  course  of  the  period 
of  lactation.  The  casein  of  cow's  milk  is  precipitated 

1  Richmond  says :  "As  the  milk  is  kept  the  amount  of  oxygen 
decreases  and  that  of  carbon  dioxide  increases;  this  is  probably 
due  to  aerobic  microorganisms,  which  absorb .  the  oxygen  and  give 
out  carbon  dioxide."  [L.  P.] 


MILK  HYGIENE       - 

by  chymosin  as  a  firm,  jelly-like  mass.  The  butter-fat 
contains  a  yellow  coloring  stuff. 

The  qualitative  composition  of  cow's  milk  averages 
as  follows  (Fleischmann) :  water,  87.75  per  cent.;  fat, 
3.4  per  cent.;  casein,  3.0  per  cent.;  albumen,  0.5  per 
cent. ;  lactose,  4.6  per  cent. ;  salt,  0.75  per  cent.2  Lacto- 
globulin  and  lecithin  are  found  only  in  very  slight  quan- 
tity; citric  acid  is  found  in  quantities  of  from  0.1  to 
0.15  per  cent.  Analysis  of  the  ash  shows  its  constitu- 
ents to  be  present  in  the  following  proportions : 

K2O        Na^O         CaO         MgO      Fe2  O3       P2  O5        Cl        SO, 
25.81         11.78         19.71         2.77          0.13         23.11      16.15    4.07  % 

But  there  may  be  a  considerable  amount  of  variation, 
especially  in  the  potash,  magnesia,  chlorine  and  sul- 
phuric acid,  since  the  consumption  of  certain  salts  in 
great  quantity  cause  changes  in  the  composition  of  the 
ash.  The  quantitative  composition  of  cow's  milk  varies 
greatly  among  the  different  breeds  and  individuals,  and 
at  different  stages  of  the  period  of  lactation  (see  the 
next  section). 

Zebu's  Milk  coincides  almost  wholly  in  its  properties 

2  Richmond  gives  the  following  average  composition  of  milk, 
based  on  the  analysis  of  200,000  samples  taken  from  the  supply  of  a 
dairy  company  in  London: 

Per  cent.  Per  cent. 

Water 87.10          Casein 3.00 

Fat 3.90          Albumin 0.40 

Milk  sugar 4.75          Ash 0.75 

A  very  large  proportion  of  the  cows  producing  milk  for  the 
London  market  are  of  the  Shorthorn  breed.  [L.  P.] 

The  following  is  taken  to  represent  "  milk  of  good  average 
quality  "  in  Massachusetts : 

Per  cent.  Per  cent. 

Water 87.00          Casein 3.00 

Fat 4.00          Albumin 0.50 

Milk  sugar 4.80          Ash 0.70 

(Bulletin  110,  Hatch  Experiment  Station.)    [L.  P.] 


THE  COMPOSITION  OF  MILK  23 

and  quantitative  composition  with  ordinary  cow's  milk. 

Buffalo's  milk,  which  possesses  a  slight,  pleasing  odor 
and  taste,  is  richer  in  solids  than  cow's  milk,  since  the 
quantity  of  fat  amounts  to  about  8  per  cent.,  the  proteids 
to  fully  4  per  cent,  and  lactose  to  4.75  to  5.2  per  cent. 

Goat's  milk  is  pure  white,  without  especially  pro- 
nounced odor  or  taste.  If,  however,  the  milking  takes 
place  in  the  stable  in  which  male  goats  are  kept,  the 
milk  very  easily  absorbs  the  same  characteristic  un- 
pleasant odor.  The  chemical  composition  of  goat's 
milk  is  similar  to  that  of  cow's  milk;  frequently,  though, 
the  fat  content  is  a  little  greater.  The  butter-fat  is  white. 

Sheep's  milk  is  a  whitish  yellow,  rather  thick  and  pos- 
sesses a  peculiar,  somewhat  unpleasant  taste  and  odor. 
It  differs  from  cow's  milk  and  goat's  milk  in  its  high 
fat  and  casein  content,  averaging  about  9.0  per  cent,  and 
6.3  per  cent,  respectively.  Moreover,  the  fat  content  is 
very  variable,  for  with  some  breeds  it  amounts  to  11  to 
12  per  cent,  and  even  more,  while  with  others  it  amounts 
to  only  2  to  3  per  cent.  The  examination  of  milk  of  2,700 
sheep  (Sartori)  showed  an  average  specific  gravity 
1.0374  and  the  following  composition:  water  78.70  per 
cent.,  fat  8.94  per  cent.,  proteids  6.3  per  cent.,  lactose 
5.06  per  cent.,  ash  1.015  per  cent.  The  average  analyses 
for  250  other  sheep  (Fleischmann)  were  as  follows: 
water  75.54  per  cent.,  fat  11.90  per  cent.,  casein  5.83 
per  cent.,  albumin  1.33  per  cent.,  lactose  3.43  per  cent., 
ash  1.05  per  cent. 

Mare's  milk  is  usually  distinctly  alkaline  to  litmus, 
but  may  be  neutral.  It  is  white  or  bluish  in  color  and 
has  a  somewhat  pronounced  sweet  taste  due  to  its  high 
lactose  content  (about  6.6  per  cent.).  The  proportions 
of  fat  and  proteids  are  conspicuously  small;  as  in  the 
averages  of  15  analyses  (Veith)  only  1.09  per  cent,  fat 
and  1.89  per  cent,  proteids  (of  which  about  a  third  was 


24  MILK  HYGIENE 

albumin)  were  present.  The  inorganic  salts  (ash)  are 
present  only  in  small  quantity  (0.31  per  cent.). 

Ass's  milk  is  essentially  the  same  as  that  of  the  mare ; 
it  has  in  common  with  the  latter  the  low  fat  and  proteid 
content  and  the  large  quantity  of  lactose.  The  composi- 
tion is  given  somewhat  differently  by  different  writers. 
Ellenberger,  Seeliger  and  Klimmer  found  as  the  aver- 
age of  a  large  number  of  analyses :  water  91.20  per  cent., 
fat  1.10  per  cent.,  proteids  1.50  per  cent.,  lactose  6.0  per 
cent.,  ash  0.40  per  cent.  The  reaction  is  decidedly  alka- 
line to  litmus.  On  account  of  the  small  proportion  of 
salts,  the  casein  is  precipitated  by  rennet  as  a  flocculent, 
disunited  mass.  Milk  of  the  ass  more  nearly  resembles 
human  milk  than  does  that  of  any  other  animal,  and  in 
Southwestern  Europe,  for  the  most  part,  milk  of  the  ass 
is  the  principal  substitute  used  for  the  nourishment  of 
infants. 

Woman's  milk,  which  reacts  amphoterically,  is  regu- 
larly somewhat  richer  in  lactose  than  cow's  milk,  but  it 
contains  less  proteids  and  also  less  ash,  especially  phos- 
phoric acid  and  lime.  While  the  lactalbumin  in  cow's 
milk  constitutes  but  one-fifth  to  one-sixth  of  the  protein, 
in  human  milk  during  the  first  part  of  the  period  of 
lactation,  albumin  and  casein  are  present  in  almost 
equal  quantities;  later,  casein  increases  a  little.  The 
average  percentage  of  fat  is  approximately  the  same  as 
in  cow's  milk,  but  it  varies  considerably,  from  1.3  per 
cent,  to  7.8  per  cent.  Human  milk  is  richer  in  lecithin, 
but  poorer  in  citric  acid  (about  0.5  per  thousand)  than 
cow's  milk.  According  to  E.  Gottlieb  the  following 
numbers  represent  the  average  composition  of  104  sam- 
ples :  water  87.92  per  cent.,  fat  3.43  per  cent.,  casein  0.58 
per  cent.,  albumin  0.52  per  cent,  lactose  7.12  per  cent., 
ash  (salts),  0.25  per  cent.  Woman's  milk  is  subject  to 
individual  variations  to  a  great  degree,  as  is  shown  by 


THE  COMPOSITION  OF  MILK  25 

the  table  below,  which  is  taken  from  Gottlieb's  analyses : 


Water. 

Fat. 

Casein. 

Albumin. 

Lactose. 

Ash. 

"Normal"  milk 

87.52 

3.38 

0.78 

0.39 

7.51 

0.27 

Rich,  milk 

8524 

5.91 

087 

036 

724 

024 

Poor  milk  

89.65 

1.66 

0.57 

0.27 

7.47 

0.23 

Each  number  represents  the  average  of  four  analyses 
taken  several  days  apart.  Each  sample  came  from  a 
young  woman  who  had  been  confined  a  few  months 
before. 

It  has  often  been  said  that  casein  in  human  milk  dif- 
fers chemically  from  that  of  cow's  milk;  but,  as  stated 
above,  according  to  the  investigations  of  recent  years, 
there  is  good  reason  to  believe  that  this  is  not  the  case. 
(Hammersten,  Cohnheim.) 

Sow's  milk  is  thick,  slimy  and  of  alkaline  reaction.  In  chemical 
composition  it  is  very  variable,  especially  so  in  regard  to  the  fat 
content  which  varies  between  1.0  per  cent,  to  more  than  12.0  per  cent. 
In  some  of  the  analyses  reported,  it  appears  that  a  distinction  has 
not  been  made  in  relation  to  the  proportion  of  fat  of  the  milk 
that  was  drawn  first  and  that  drawn  last,  but  since  the  other 
ingredients  of  the  milk  were  found  in  different  proportions,  the 
variation  can  not  be  doubted.  The  quantity  of  protein  averages 
about  6.0  per  cent,  but  may  vary  from  5.7  to  15.5  per  cent.  The 
quantity  of  lactose  varies  from  2.0  per  cent,  to  3.8  per  cent.,  the 
ash  from  0.77  per  cent,  to  1.18  per  cent.  On  the  whole,  it  may  be 
said  that  sow's  milk  is  quite  concentrated. 

Bitch's  milk  is  also  quite  variable  in  its  composition.  The 
fat  content  varies  between  4.0  per  cent,  and  12.0  per  cent.,  the  pro- 
portion of  casein  between  about  3.5  per  cent,  and  6.0  per  cent., 
albumin  is  present  in  about  the  same  quantity  as  casein,  there  is 
about  2.0  per  cent,  to  3.0  per  cent,  of  lactose  and  about  1.0  per 
cent,  of  ash. 

The  milk  of  the  cat  has  not  received  much  study.  According 
to  some  analyses  that  have  been  made  (by  Cornaille),  it  is  of  about  the 


MILK  HYGIENE 


following  composition :  fat  3.33  per  cent.,  casein  3.12  per  cent.,  albu- 
min 5.96  per  cent.,  lactose  about  4.9  per  cent.,  and  ash  0.59  per  cent. 

The  rabbit  and  the  reindeer  give  milk  particularly  rich  in  fat  and 
especially  concentrated,  but  poor  in  lactose.  The  milk  of  the 
elephant  shows  very  great  fat  and  sugar  content  and  comparatively 
little  protein. 

A  milk  differing  greatly  from  the  usual  is  that  of  the  whale. 
It  contains  only  from  41.0  per  cent,  to  48.0  per  cent,  of  water,  and 
fat  in  the  enormous  proportion  of  43.0  per  cent,  to  45.0  per  cent. 
There  is  7.5  per  cent,  to  11.0  per  cent,  of  protein  and  only  about 
1.3  per  cent,  of  sugar. 

The  table  below  shows  the  average  analysis  of  human 
milk  and  of  the  other  kinds  of  milk  used  as  food  for  man : 


Cow. 

Goat, 

Sheep. 

Ass. 

Mare. 

Woman. 

Water  

87.75 

87.30 

75.54 

91.20 

90.00 

87.92 

Casein  

3.00 

3.00 

5.83 

0.90 

1.26 

0.58 

Albumin  

050 

050 

133 

060 

063 

052 

Fat  

3.40 

3.90 

11.90 

1.10 

1.09 

3.43 

Lactose  

4.60 

4.40 

3.43 

6.00 

6.65 

7.12 

Salts 

075 

080 

1  05 

040 

031 

025 

IV.    VARIATIONS  IN  THE  COMPOSITION 
OF  COW'S  MILK 

It  has  already  been  stated  that  the  composition  of 
the  milk  of  the  cow,  as  well  as  that  of  other  animals,  may 
vary  more  or  less.  So  far  as  the  variations  of  cow's 
milk  are  concerned,  they  are  not  very  great,  still  they 
are  of  sufficient  importance  to  make  it  necessary  to 
take  them  into  consideration  in  connection  with  its  pro- 
duction, sale  and  control.  The  above  figures  give  ap- 
proximately the  average  composition  of  cow's  milk  and, 
of  course,  correspond  with  the  composition  of  market 
milk,  which  consists  of  a  mixture  of  milk  of  several  or 
many  cows.3  The  separate  constituents  vary  in  quantity 

n  These  are  Danish  figures;  in  America  the  average  for  market 
milk  is  higher.  [L.  P.] 


VARIATIONS  IN  COW'S  MILK  27 

in  different  degrees,  the  fat  content  varying  the  most, 
the  albumin,  lactose  and  ash  ingredients  less.  In 
' '  rich  ' '  milk  the  fat  content  often  considerably  exceeds 
the  average,  while  the  proportions  of  protein  and  lac- 
tose are  never  much  higher  than  the  averages  given. 
On  the  other  hand,  with  thin,  poor  milk  the  fat  per  cent, 
may  fall  far  below  the  average,  while  the  proportions  of 
protein  and  lactose  depart  but  slightly  from  the  average. 
These  variations  are  not  due  merely  to  the  elimination 
of  water  from  the  milk,  that  is,  to  a  simple  concentration, 
but  rather  to  a  qualitative  variation  in  the  activities  of 
the  gland  cells. 

Just  as  is  the  case  with  other  glands,  the  milk 
glands  may  be  stimulated  to  greater  activity,  so  that  the 
quantity  of  secretion  increases,  but  its  chemical  compo- 
sition is  not  disturbed,  or  only  slightly,  or  temporarily, 
until  the  gland  tissue  has  accustomed  itself  to  the 
new  condition.  Drinking  a  large  quantity  of  water 
causes  no  increase  in  milk  secretion;  the  gland  cells  do 
not  secrete  more  water  than  the  quantity  required  to 
maintain  the  proper  proportion  to  the  milk  solids.  Food 
containing  much  water  has  no  permanent  effect  upon 
the  composition  and  the  quantity  of  the  milk.  The 
influence  of  such  materials  as  pilocarpine  and  atropine, 
which  increase  or  reduce  other  secretions  in  a  great 
degree,  have  no  direct,  or  only  a  very  slight  influence 
on  the  milk  secretion,  apparently  because  this  is  con- 
trolled by  the  sympathetic  nerve  centres.  The  various 
conditions  that  have,  or  are  believed  to  have,  an  influence 
upon  the  chemical  composition,  and  especially  upon  the 
fat  content  of  milk,  are  considered  in  the  following  para- 
graphs. 

1.  Breed  peculiarities.  Cows  of  different  breeds 
give  milk  of  somewhat  different  composition.  In  gen- 
eral, it  is  believed  that  breeds  from  the  highlands  and 


28  MILK  HYGIENE 

mountainous  regions  give  a  richer  milk,  while  breeds 
from  the  lowlands  yield  milk  poorer  in  fat.  There  are, 
it  is  true,  exceptions  to  this  rule,  e.g.,  the  Allgauer  and 
the  brown  Swiss  cattle  give  rather  a  poor  milk,  while 
the  Devons  and  the  Normandy  cattle  give  milk  rich  in 
fat.  As  an  example  of  breeds  that  give  milk  especially 
rich  in  fat  we  may  mention  the  Jerseys  and  the  Guern- 
seys, whose  milk  contains  an  average  of  4.5  per  cent, 
to  5.5  per  cent,  fat,  also  the  Harz  cattle,  whose  milk  is 
reported  to  contain  an  average  of  5.8  per  cent.  fat.  On 
the  other  hand,  milk  of  the  Swiss  cows  has  only  3.0 
per  cent,  fat,  that  of  the  Angler  and  Breitenburger  and 
other  breeds  only  about  3.13  per  cent,  to  3.15  per  cent, 
fat.  The  average  of  the  Danish  breeds  can  hardly  be 
placed  higher,  being  about  3.2  per  cent,  to  3.4  per  cent, 
fat. 

2.  Individual  peculiarities.  The  figures  given  above 
are  averages  only.  The  milk  of  different  individuals 
varies  more  or  less  so  that  in  the  same  breed  there  are 
individuals  that  give  milk  rich  in  fat,  and  also  those 
whose  milk  has  a  percentage  of  fat  below  the  average 
of  the  breed  in  question.  The  production  of  rich  milk  is, 
therefore,  a  distinctly  individual  property  that  is  due 
to  the  physiological  peculiarities  of  the  gland  cells  of  the 
animal,  and  which  appears,  to  a  great  degree,  to  be 
hereditary.  Among  cows  of  the  same  breed  may  be  found 
some  whose  milk  contains  4.0  per  cent,  or  more  of  fat 
and,  on  the  other  hand,  there  are  many  that  give  milk 
containing  only  about  2.5  per  cent,  fat ;  indeed,  not  infre- 
quently the  percentage  of  fat  is  still  lower,  and  from 
Germany  there  are  records  of  cows  that  give  milk  con- 
taining not  more  than  1.5  per  cent,  of  fat.  Such  cows 
are  frequently  and  in  large  numbers  excluded  from  the 
best  herds,  so  when  herds  are  made  up  of  purchased 
cows,  the  mixed  milk  from  such  cattle  often  contains  but 


VARIATIONS  IN  COW'S  MILK  29 

little  fat  and  may  not  exceed  2.25  per  cent,  to  2.75  per 
cent.4 

While  it  is  scarcely  possible,  as  will  be  discussed 
later,  to  influence  the  composition  of  milk  materially  or 
permanently  by  alterations  in  the  quantity  and  com- 
position of  the  food,  still  it  may  not  be  entirely  impossi- 
ble to  influence  the  young  animal  by  skilful  or  by 
appropriate  feeding  in  such  a  way  as  to  encourage  it 
later  to  produce  milk  rich  in  fat.  But  thoroughly 
reliable  data  on  this  point  are  not  available. 

3.  The  age  of  the  cow.     Although  the  quantity  of 
milk  varies  according  to  the  age  of  the  cow,  so  that  it  is 
usually  greatest  during  the  third  to  the  fifth  lactation 
periods,  the  chemical  composition  appears  to  remain 
almost  unchanged  from  year  to  year  (Hittcher)  ;  yet  it 
is    apparent    that    fats    as    well    as    other    ingredients 
decrease  with  great  age. 

4.  The  stage  of  the  lactation  period.     The  colostrum 
secretion  is  not  especially  important.     The  true  milk 
secretion  very  quickly  attains  a  considerable  volume,  but 
falls  off  gradually  after  a  longer  or  shorter  time,  until 
the   secretion  ceases  altogether  or  is  insignificant  to- 
wards the  end  of  the  period  of  gestation.     Some  cows, 
however,  continue  to  milk  very  well  up  to  calving  and 
to   the  new  period   of  lactation.     It  was   emphasized 
above  that  colostrum  differs  essentially,  both  morpho- 
logically and  chemically,  from  normal  milk.     Further- 
more, the  composition  of  milk  during  the  first  part  of 
the  lactation  period  differs  from  that  secreted  toward 
the  close. 

a.  Colostrum.  The  first  colostrum  is  whitish,  yellow- 
ish, or  even  reddish  to  brownish;  it  is  slimy  and  has  a 

4  It  should  be  borne  in  mind  that  the  cattle  here  referred  to 
are  of  heavy  milking  lowland  breeds  not  represented  in  America. 

[L.  P.] 


30 


MILK  HYGIENE 


specific  gravity  of  1.040  to  1.080.  Its  microscopic  ap- 
pearance has  been  described  before  and,  in  part,  its 
chemical  composition.  Gradually,  the  appearance  and 
the  composition  of  the  secretion  changes  until,  in  the 
course  of  about  a  week,  it  becomes  pure  milk.  This 
gradual  development  is  illustrated  by  the  following 
analysis  given  by  Eugling: 


Number  of  hours  after  calving. 

Normal 
milk. 

Imme- 
diately. 

10 

24 

48 

72 

Water  

73.17 
2.65 

16.56 

3.54 
3.00 
1.18 

78.77 
4.28 

9.32 

4.66 
1.42 
1.55 

80.63 
4.50 

6.25 

4.75 

2.85 
1.02 

85.81 
3.25 

2.31 

4.21 
3.46 
0.96 

86.64 
3.33 

1.03 

4.08 
4.10 
0.82 

87.75 
3.00 

0.50 

3.40 
4.60 
0.75 

Casein  

Albumin  ^ 

Globulin  / 
Extractives 

Sugar  

Ash          

These  figures  show  that  the  chief  difference  in  the 
composition  of  milk  and  colostrum  consists  in  the 
greater  albumin  and  globulin  content  of  the  latter,  which 
arises  partly  from  the  presence  of  numerous  colos- 
trum bodies,  in  consequence  of  the  presence  of  which 
colostrum  coagulates  when  heated.  Another  important 
difference  is  the  low  sugar  content  of  colostrum ;  accord- 
ing to  Tereg  the  sugar  of  colostrum  is  not  lactose,  but  is 
grape  sugar,  or  perhaps  a  mixture  of  this  and  galactose. 
Of  the  substances  that  are  extracted  with  the  fat,  about 
13.8  per  cent,  consists  of  cholesterin  and  8.0  per  cent, 
of  lecithin. 

Among  other  peculiarities  shown  by  colostrum  of  the 
cow  may  be  mentioned  its  acid  reaction  and  the  fact  that 
after  the  addition  of  rennet  it  does  not  coagulate  at  all, 
or  only  very  slowly. 

b.    Milk.    Shortly  after  calving,  while  the  secretion 


VARIATIONS  IN  COW'S  MILK  31 

is  abundant,  the  milk  is  generally  a  little  less  rich  in 
solids  and  especially  in  fat  than  it  is  later  when  the 
secretion  begins  to  fall  off;  with  some  cows  the  differ- 
ence is  not  very  great,  but  with  others  it  is  considerable. 
In  the  last  month  the  secretion  falls  off  rapidly  and 
often  ceases  entirely;  at  the  same  time  the  proportion 
of  solids  usually  increases  and  this  is  especially  the  case 
in  relation  to  fat.  The  milk  gradually  acquires  a  decided 
alkaline  reaction  to  litmus  paper  and  not  infrequently 
develops  a  salty  taste.  The  changes  in  composition 
are  shown  in  the  following  table,  which  gives  the  results 
of  analyses,  made  by  Fleischmann,  of  the  milk  of  one 
cow  which  calved  January  28th. 

With  this  cow,  the  percentage  of  fat  during  the 
period  of  lactation  rose  from  3.033  to  8.300;  but  this 
significant  increase  occurred  almost  entirely  in  the  last 
month  when  the  cow  had  become  an  old  milker.  At  the 
same  time  the  quantity  of  albumin,  lactose  and  salt 
(i.e.,  solids  not  fat)  increased  only  from  8.14  per  cent, 
to  9.00  per  cent. 

The  chemical  composition  of  milk  of  some  cows  does 
not  change  noticeably  during  the  whole  period  of  lac- 
tation, and  the  percentage  of  fat  as  well  as  the  other 
solids  may  even  fall  off  a  little  at  the  end  of  the  lactation 
period.  Fleischmann  gives  a  table  showing  analyses  of 
the  milk  of  such  a  cow  for  the  whole  lactation  period: 
the  daily  quantity  of  milk  in  April  was  19.84  kg.,  on  the 
31st  of  January  following  it  was  3.6  kg.  The  fat  per- 
centage, which  had  varied  between  2.56  and  2.97,  fell  in 
January  to  2.42,  2.60,  2.32,  and  2.48  upon  different 
analyses.  The  percentage  of  solids  not  fat  also  fell  a 
little. 

5.  The  time  and  method  of  milking.  It  is  commonly 
believed  that  there  is  always  a  slight  difference  between 
the  chemical  composition  of  the  morning  and  the  even- 


32 


MILK  HYGIENE 


ing  milk  in  that  the  latter  is  richer  in  fat  than  the  for- 
mer. Numerous  investigations  have  given  very  varia- 
ble results  that  may  be  explained  by  the  short  duration 
of  the  test,  by  the  daily  variations  of  the  composition 
of  the  milk,  etc.  Some  larger  experiments  relating  to 

LACTATION  PERIOD 


Daily 
quantity 
of  milk. 
Kg. 

Specific 
gravity. 

Fat. 
'  Per  cent. 

Solids 
not  fat. 
Per  cent. 

Fat  content 
of  the  total 
s  .lids. 
Per  cent. 

April  
May 

11.55 
11.95 

1.0291 
1.0290 

3.033 
3  264 

8.140 

8  166 

27.15 
2856 

June 

1045 

10287 

3  405 

8  113 

2956 

July  .  . 

8.82 

1.0283 

3.458 

8027 

3011 

August                  

9.66 

1.0287 

3586 

8149 

3057 

September 

9.07 

10289 

3650 

8  230 

30  72 

October   

7.07 

1  .0292 

3.434 

8.247 

2939 

November      

6.63 

1.0299 

3823 

8501 

3101 

December  

5.11 

1.0300 

4.2(57 

8.616 

33.11 

January    2  

3.0 

1.0302 

5.050 

8.823 

36.40 

January    3 

2.7 

1.0300 

5.400 

8843 

3791 

January    4 

28 

10299 

4720 

8680 

3522 

January    6  
January    7  

2.3 

2.4 

1.0307 
1  .0299 

5.470 
5.440 

9.032 

8.824 

37.71 

3814 

January    8 

23 

1  0304 

5250 

8911 

3707 

January    9 

23 

10310 

5200 

9054 

3648 

Janur.ry  10  

2.1 

1.0308 

5.090 

8.980 

36.17 

January  11 

22 

1.0308 

5  100 

8982 

3622 

January  14 

1  9 

10277 

6900 

8565 

4460 

January  16  
January  ]  8  

1.3 

1.4 

1.0301 

1.0288 

8.300 
7.480 

9.446 
8.958 

46.77 
45.50 

many  animals  and  extending  over  a  long  period,  have 
proven  that  the  morning  inilk  does  not  differ  from  the 
evening  milk  in  fat  content  when  the  period  between 
the  milkings  is  equally  great  and  the  feed,  the  amount 
of  drinking  water  taken,  etc.,  are  the  same.  But  in  prac- 
tice this  is  not  the  case,  because  usually  a  small  dif- 
ference exists,  so  that  where  there  is  a  larger  quantity 


VARIATIONS  IN  COW'S  MILK  33 

of  milk  there  is  a  smaller  percentage  of  fat.  Fleisch- 
mann  found  by  continuous  investigations  of  one  herd  of 
120  to  130  cows  during  one  year,  that  on  the  average  for 
the  whole  year  the  morning  milk  contained  a  little  more 
fat  than  the  evening  milk  (3.260  per  cent,  against  3.183 
per  cent.),  while  the  quantity  of  morning  milk  was  a 
little  less  than  that  of  the  evening  milk  (4.143  kg.  against 
4.616  kg.). 

There  is  a  slight  difference  dependent  upon  the  sea- 
sons ;  it  has  been  shown  that  in  the  summer  the  morning 
milk  contains  a  slight  excess  of  fat  while  in  the  winter 
the  evening  milk  is  the  richer.  It  follows  that  since  the 
quality  of  milk  is  influenced  by  external  influences,  there 
can  be  no  general  rule  to  define  the  difference  between 
morning  and  evening  milk  but,  usually,  if  no  other  con- 
ditions arise,  this  difference  is  comparatively  small. 

It  is  commonly  believed  that  three  milkings  a  day 
cause  not  only  the  production  of  a  greater  quantity 
of  milk,  but  also  a  somewhat  greater  percentage  of  fat, 
but  it  can  scarcely  be  said  that  there  is  definite  proof  of 
an  increase  in  the  percentage  of  fat. 

If  the  milking  is  done  by  a  strange  or  inexperienced 
person,  the  flow  is  diminished.  This  also  influences  the 
quality  of  the  milk.  The  first  and  the  last  milk  drawn 
differ  greatly  in  fat  content.  It  is  supposed  that  the  fat 
globules  adhere  firmly  to  the  walls  of  the  ducts,  as  a 
layer  of  cream,  and  are  freed  from  these  only  with  dif- 
ficulty. The  following  figures  show  the  results  of 
analyses  by  de  Vriezes,  who  found  in  the  first  streams 
1.2  per  cent,  fat;  after  drawing  about  one-quarter  the 
quantity  of  milk,  2.1  per  cent,  fat;  after  drawing  about 
one-half  the  quantity  of  milk,  3.6  per  cent,  fat;  after 
drawing  about  three-quarters  the  quantity  of  milk,  5.2 
per  cent,  fat ;  in  the  last  milk,  7.1  per  cent,  fat ;  in  the 
very  last  drops  of  milk  drawn,  10.0  per  cent.  fat. 

3 


34 


MILK  HYGIENE 


Therefore,  by  milking  a  single  cow,  one  can  obtain 
inilk  of  the  greatest  variety  of  fat  content,  which  must 
be  considered  when  samples  are  taken  from  individual 
animals  for  the  purpose  of  examination.  According  to 
Hittcher's  investigations,  the  situation  seems,  singularly 
enough,  to  be  wholly  changed  if  the  calf  is  permitted  to 
suck  the  cow;  the  milk  that  remains  is  not  rich,  but  is 
much  poorer  in  fat. 


Number  of  the 
cow. 

Fats.     Percent. 

Solids  not  fat.    Per  cent. 

Minimum. 

Maximum. 

Minimum. 

Maximum. 

1 

2.621 

4.698 

7.859 

8.771 

2 

2.160 

3.404 

7.293 

8.707 

3 

.... 

4 

2.163 

3.965 

7.702 

8.743 

5 

2.543 

3.900 

7.636 

8.577 

6 

2.096 

3.446 

7.753 

8.893 

7 

2.257 

3.837 

7.974 

8.914 

8 

2.690 

4.117 

7.943 

8.897 

9 

2.566 

4.709 

8.197 

10.050 

10 

2.464 

6.000 

7.728 

8.939 

11 

2.741 

4.649 

8.305 

9.371 

12 

2.509 

5.505 

8.582 

9.550 

13 

2.645 

4.724 

8.389 

9.623 

14 

2.097 

4.173 

8.394 

9.131 

15 

2.437 

4.234 

8.031 

9.046 

16 

2.326 

4.637 

8.040 

9.363 

17 

.... 

.... 

18 

2.537 

4.390 

8.098 

9.170 

The  opinion  expressed  in  recent  years,  that  by 
a  special  method  of  milking  the  average  fat  percent- 
age of  milk  of  individual  cows  may  be  raised,  is  in- 
correct. 

6.  Daily  variations.  Daily  examinations  of  milk  of 
individual  cows  show  that  not  only  the  quantity  of  milk 
undergoes  change  from  day  to  day,  but,  at  the  same 


VARIATIONS  IN  COW'S  MILK 


35 


time,  strange  to  say,  the  chemical  composition  of  the 
milk  is  subjected  to  daily  variations  that  may  reach 
considerable  extent.  Knowledge  of  this  is  naturally  of 
the  greatest  importance  in  the  detection  of  milk  adul- 
teration. The  table  on  page  34  is  given  by  Fleischmann 
to  show  the  minimum  and  maximum  fat  percentages  in 
the  milk  of  a  series  of  cows  examined  daily  during  an 
entire  period  of  lactation. 

As  is  shown,  the  percentages  of  fat  differ  consider- 
ably even  in  milk  from  the  same  cow ;  one  cow,  number 
12  in  the  table,  produced  milk  differing  in  fat  content 
as  much  as  100  per  cent.,  that  is,  from  2.509  to  5.505  per 
cent. 


Cow  No.  I. 

Cow  No.  V. 

Cow  No.  VII. 

Cow  No.  VIII. 

3.214 

3.040 

2.566 

3.551 

2.869 

2.825 

.... 

3.592 

2.859 

3.322 

3.080 

3.244 

2.862 

3.314 

2.932 

.... 

3.043 

2.822 

2.790 

3.294 

3.790 

2.329 

3.047 

3.070 

2.996 

2.308 

2.847 

3.369 

2.616 

2.816 

3.685 

3.272 

3.334 

3.199 

3.749 

3.189 

3.381 

3.732 

4.031 

3.267 

3.402 

3.620 

3.927 

3.068 

3.316 

3.522 

3.792 

3.795 

3.344 

3.492 

3.844 

3.470 

2.970 

3.633 

The  variations  are  not  always  gradual,  but  occur 
spasmodically,  as  is  evident  from  the  figures  above, 
taken  from  Fleischmann 's  work  on  milk.  The  numbers 
in  the  perpendicular  columns  give  the  percentage  of 
fat  for  successive  days;  the  figures  above  the  dividing 
line  date  from  the  beginning  of  the  lactation  period  of 
the  cows,  while  below  the  line  the  figures  given  refer  to 


36  MILK  HYGIENE 

the  end  of  the  milking  period.  The  examples  are  chosen 
in  order  to  make  plain  the  daily  variations  with  the 
individual  animals. 

One  may  find  even  greater  variations  by  examining 
the  morning  and  evening  milk.  As  examples,  some  re- 
sults are  given  from  the  daily  examinations  of  milk  from 
the  above  mentioned  cows  number  I  and  number  V,  the 
figures  referring  alternately  to  the  morning  and  the 
evening  milk  on  successive  days : 

Cow  No.  I.          Cow  No.  V. 

Morning 3.375  3.180 

Evening 2.640  2.940 

Morning 3.240  2.710 

Evening 3.995  2.900 

Morning 2.750 

Evening —  3.700 

Morning 3.800 

Evening 3.250 

Morning 4.100  2.360 

Evening 3.815  3.560 

Morning 4.145  4.530 

Evening 3.485  3.180 

Morning 4.085  3.220 

Evening 2.785  2.800 

Morning -  3.690 

Evening 3.590  3.100 

The  changes  in  the  quantity  of  solids  not  fat  (protein, 
lactose  and  salts),  as  is  apparent  from  the  above  tables, 
are  much  less  than  those  of  the  fat,  and  especially  do 
lactose  and  salts  vary  but  little. 

The  reasons  for  these  daily  variations  in  the  quan- 
titative composition  of  milk  are  not  yet  wholly  under- 
stood, but  are  to  be  sought  in  everything  that  in  any 
way  has  an  unfavorable  influence  on  the  animal ;  changes 
of  food  (see  below)  or  of  the  times  of  feeding  and  drink- 
ing, changing  to  a  strange  place,  restlessness  in  the  sta- 
ble, storms,  O3strum,  changes  at  milking,  etc.  Very  often 
no  definite  reason  can  be  discovered  and  it  appears  that 


VARIATIONS  IN  COW'S  MILK  37 

such  variations  may  take  place  without  external  causes. 
With  cows  that  have  suckled  their  calves,  after  separa- 
tion from  the  calf,  there  is  usually  a  very  noticeable  de- 
crease of  fat  in  the  milk,  which  is  sometimes  made  good 
by  a  subsequent  considerable  temporary  increase. 

7.  The  influence  of  food.  It  is  an  old  and,  in  some 
places,  still  commonly  accepted  opinion  that  the  compo- 
sition and  the  quantity  of  the  food  have  an  important 
influence  on  the  composition  of  the  milk  and  more  espe- 
cially on  its  fat  content.  Palm  and  cocoanut  meal  and 
several  other  food  stuffs,  are  said  to  encourage  the  pro- 
duction of  rich  milk,  while,  on  the  other  hand,  distillery 
slops,  for  example,  are  said  to  cause  the  production  of 
poor  milk.  During  recent  years,  numerous  investiga- 
tions undertaken  abroad  as  well  as  in  the  experimental 
laboratory  in  Copenhagen,  seem  to  have  proven  that  it 
is  not  possible  by  changes  of  food  to  bring  about  a 
noticeable  permanent  effect  upon  the  composition  of  the 
milk.  The  activity  of  the  udder  cells,  as  is  shown  from 
the  daily  variation  in  the  composition  of  milk,  is  easily 
thrown  out  of  equilibrium,  but  such  a  condition  is  only 
temporary.  With  changes  of  feeding,  this  condition 
appears  quite  plainly,  nearly  every  change  very 
quickly  causing  a  variation  in  the  composition  of  the 
milk,  especially  the  fat  percentage,  so  that  sometimes 
this  rises,  sometimes,  e.g.,  when  distillery  slops  and  simi- 
lar moist  foods  are  fed,  it  falls  off  more  or  less.  But 
this  variation  always  seems  to  be  merely  temporary ;  in 
the  course  of  a  day  or  so,  sometimes,  however,  not  until 
the  end  of  a  couple  of  weeks,  the  average  percentage 
returns.  This  is  the  case  even  when  food  of  only  one 
kind,  as  distillery  slop  and,  indeed,  when  food  especially 
rich  in  fat,  is  fed;  in  these  cases,  also,  the  change  in 
percentage  will  be  only  temporary  (Henriques  and  C. 
Hansen). 


38  MILK  HYGIENE 

To  be  sure,  there  are  many  reports  in  print  of 
other  results,  but  upon  examination  these  are  found  to 
extend  over  so  short  a  period  that  the  temporary 
changes  had  not  yet  disappeared,  or  they  refer  to  inves- 
tigations with  different  cows  whose  milk  was  not  suf- 
ficiently examined,  or  to  cows  that  did  not  receive  the 
same  food  in  the  beginning  of  the  experiment,  or,  finally, 
sufficient  allowance  was  not  made  for  the  daily  varia- 
tions and  for  those  that  occur  at  different  stages  of  the 
lactation  period. 

The  temporary  changes  in  the  composition  of  milk 
which  occur  after  a  change  in  the  food,  may  be  consid- 
erable, but  here,  too,  the  question  of  individual  peculiari- 
ties enters,  so  that  the  changes  shown  by  two  cows  under 
the  same  conditions  may  differ  materially. 

It  is  of  an  old  belief,  that  the  change  from  dry  food 
to  green  causes  an  increase  in  the  fat  content  of  the  milk. 
The  investigations  in  the  Danish  experimental  labora- 
tory have  proven  this ;  they  show  that  the  fat  percent- 
age under  these  conditions  may  increase  0.5  per  cent., 
with  some  cows  it  increased  even  1.0  per  cent.,  but  this 
increase  lasted  only  a  few  weeks.  Also,  when  changing 
the  ration  to  include  some  of  the  oil  cakes,  a  similar 
increase  in  the  percentage  of  fat  has  been  observed,  but 
seldom  more  than  about  0.5  per  cent.  On  the  other 
hand,  as  stated  before,  there  are  observations  of  tem- 
porary falling  of  the  fat  from  0.25  per  cent,  to  0.5  per 
cent,  when  a  change  of  food  is  made  to  distillery  slops 
or  similar  rations. 

It  is,  then,  possible  to  show  that  the  udder  reacts 
rather  characteristically  to  certain  changes  in  the  ration 
and  especially  to  some  food  stuffs ;  but  this  reaction  is 
lost  when  the  cow  has  become  accustomed  to  the  new 
food.  Under  such  conditions,  simultaneously  with  the 
increase  of  the  fat  percentage  there  frequently  occurs  a 


VARIATIONS  IN  COW'S  MILK  39 

decrease  in  the  quantity  of  milk,  while,  on  the  other 
hand,  a  lessening  of  the  percentage  of  fat  is  often  accom- 
panied by  an  increase  in  the  volume  of  the  milk. 

Although  recent  experiments  have  thrown  much 
light  upon  the  influence  of  food  on  the  milk  secretion,  yet 
there  is  need  for  further  information  on  many  points. 
For  instance,  it  is  not  known  with  certainty  if  it  is  pos- 
sible by  long  continued,  particularly  unfavorable,  one- 
sided composition  of  food,  to  produce  lasting  changes 
in  the  fat  content  of  milk  and  in  the  solids  not  fat. 

Lactose  occurs  in  milk  in  but  one  form  and  the  char- 
acter of  proteids  is  not  affected  by  the  nature  of  the 
foods.  On  the  other  hand,  the  milk  fats  vary,  sometimes 
there  is  more  and  sometimes  less  olein,  which  affects  the 
consistency  of  the  butterfat,  and  the  percentages  of  vola- 
tile fatty  acids  may  vary  considerably.  It  has  often  been 
said  that  the  fats  taken  with  the  food  do  not  pass  un- 
changed into  the  milk.  Only  when  a  great  quantity  of 
food,  rich  in  a  kind  of  fat  that  can  be  distinguished 
chemically,  is  fed,  is  it  possible  to  find  small  quantities 
of  that  fat  in  the  butterfat  of  the  milk. 

But  little  is  known  positively  concerning  the  causes 
of  the  variations  in  the  composition  of  the  butter- 
fat  and  especially  concerning  the  influence  of  the  food 
upon  it.  The  milk  fat  may  originate  in  the  fatty  tissue 
of  the  animal,  from  the  fat  stuffs  taken  with  the  food 
and,  apparently,  also,  directly  from  the  carbohydrates 
consumed.  There  are  a  number  of  other  conditions, 
as  the  composition  of  the  ration,  excessive  feeding 
with  fatty  foods,  starvation,  etc.,  that  have  some  in- 
fluence in  this  direction  but,  as  they  are  of  no  sanitary 
importance,  it  is  unnecessary  to  discuss  them  here  in 
detail. 

It  is  generally  believed  that  odors  and  tastes  pass 
from  the  food  that  is  consumed  into  the  milk.  The 


40  MILK  HYGIENE 

milk  of  the  Alpine  cows  is  noted  for  its  aromatic 
taste.  Feeding  with  beet  leaves,  turnips,  malt  sprouts, 
etc.,  is  supposed  to  be  the  cause  of  the  taste  and  odor  of 
beets  or  a  burnt  taste  and  odor  in  the  milk.  We  do  not 
yet  know  how  much  influence  is  to  be  attributed  to  the 
food.  In  some  cases,  the  offensive  odor  and  taste  is 
undoubtedly  due  to  the  activity  of  bacteria  in  the  milk — 
indeed,  it  is  doubtful  if  the  "  beet  taste  "  and  the  "  burnt 
taste  "  ever  come  from  the  food  (see  below).  Peculiari- 
ties of  breed  may  possibly  be  the  cause  of  the  aro- 
matic milk  of  the  Alpine  cows.  On  the  whole,  it  is 
highly  probable  that  the  food  has  some  influence  on  the 
taste  and  odor  of  the  milk  [this  is  unquestionable  in  the 
case  of  garlic,]  but  ~by  no  means  all  of  the  substances  in 
milk  that  have  special  odors  and  tastes  are  secreted 
with  the  milk. 

The  ash  ingredients  of  milk  are  not  generally  influ- 
enced to  a  great  extent  by  the  amount  of  salts  taken 
with  the  food;  even  a  considerable  iron  or  phosphoric 
acid  content  of  the  food  causes  no  direct  increase  of 
these  materials  in  the  milk;  still,  certain  sulphates,  as 
Glauber's  salt,  given  in  large  quantities  are  excreted  in 
small  quantity  with  the  milk,  and  consequently  cause 
an  increase  in  sulphuric  acid  in  the  ash. 

While  it  is  true  that  feeding  influences  the  compo- 
sition of  milk  only  to  a  slight  degree,  it  is  nevertheless 
true  that  the  quantity  of  milk  is  dependent  to  a  very 
great  degree  on  the  amount  and  composition  of  the  food. 

8.  The  significance  of  sexual  conditions.  The  occur- 
rence of  osstrum  and  pathological  conditions  of  the 
generative  organs  cause  a  decrease  in  the  milk  secre- 
tion ;  therefore  it  has  been  assumed  that  these  conditions 
may  also  cause  changes  in  the  chemical  composition  of 
the  secretion,  yet  this  does  not  always  appear  to  be  the 
case. 


VARIATIONS  IN  COW'S  MILK  41 

a.  (E strum  has  a  very  different  effect  on  the  milk 
secretion  of  individual  cows.    Kiihn  found  no  effect,  but 
von  Kleuze  found  such  a  great  albumin  content  that  the 
milk  could  not  be  boiled,  and  Schaffer  established  a 
remarkably  high  fat  content.  On  the  other  hand,  Fleisch- 
mann  found  only  0.714  per  cent,  fat  in  the  evening  milk 
of  a  cow  that  had  come  in  heat  in  the  course  of  the  day, 
though  the  morning  milk  contained  3.56  per  cent.  fat. 
On  the  whole,  it  may  be  said  that  normal  oestrum  often 
induces  a  passing  disturbance  of  the  normal  secretory 
activity  of  the  udder. 

b.  Nymphomania,  which  has  no  slight  influence  on 
the  nature  of  the  meat,  and  reduces  the  milk  secretion 
considerably,  probably  influences  the  nature  of  the  milk 
also.     Only  a  single  analysis  of  such  milk  is  given  by 
Schaffer;   the   quantity   of  fat   and    lactose    had    not 
changed,  but  the  quantity  of  protein  was  remarkably 
high,  namely,  5.72  per  cent. 

c.  Ovariotomy.    As  is  known,  it  is  frequently  claimed 
that  spaying  performed  on  healthy  cows  during  the  first 
months  of  the  lactation  period  causes  a  considerable 
lengthening  of  this  period,  an  increased  daily  secretion, 
and  greater  fat  content  of  the  milk.     However,  it  can 
hardly  be  said  that  this  is  sufficiently  established;  and 
especially,  it  is  not  to  be  considered  as  proven    that 
ovariotomy  is  able  to  raise  the  fat  content ;  in  fact  it  is 
most  improbable.     Ovariotomy  performed  on  nympho- 
maniac cows  causes,  among  other  things,  the  possibly 
abnormal  milk  secretion  to  return  again  to  normal. 

d.  Abortion.    The  experiments  that  were  conducted 
by  Schaffer  and  Hess  have  shown  that  abortion,  which 
has  such  great  influence  on  the  quantity  of  milk,  has  no 
influence  on  its  composition.     The  same  statement  ap- 
plies to  the  retention  of  the  afterbirth,  in  so  far  as  this 
causes  no  general  illness. 


42  MILK  HYGIENE 

9.  Exercise   and  work.     According  to   a  number   of 
different  experiments  at  hand   (Dolgich,  Torssell,  and 
several  others)  daily  exercise  increases  milk  secretion 
so  that  not  only  the  amount  of  milk  increases,  but  also 
the  total  quantity  of  fats.    Sometimes,  indeed,  the  per- 
centage of  fat  increases,  and,  as  a  rule,  the  percentage  of 
casein    diminishes,    while    the    other    constituents    are 
affected  irregularly. 

Work  does  not  necessarily  influence  the  milk  secre- 
tion to  a  great  degree  (Morgen),  but  generally  causes  a 
slight  diminution  in  quantity  and  there  is  an  increase  in 
the  percentage  of  fat  and  a  proportionate  but  smaller 
increase  in  the  percentage  of  protein  and  ash.  Exhaust- 
ing work  causes  not  only  a  material  decrease  in  the 
quantity  of  milk,  but  also  a  disturbance  in  the  whole 
secretion,  so  that  even  vegetable  fats  are  excreted  in 
the  milk  in  unchanged  condition  (Dolgich). 

10.  Disease  of  the  cow  often  brings  about  a  decrease 
and   sometimes   even  an  entire   cessation  of  the  milk 
secretion.     In  diseases  of  the  udder,  the  milk  under- 
goes, as  will  be   seen  later,  very  important  chemical 
changes.     There   is  very  little   positive  knowledge   of 
the  changes  in  the  composition  of  milk  during  diseases 
that  are  not  localized  in  the  udder.     Apparently,  it  is 
usually  the  rule  that  the  daily  variations  in  the  composi- 
tion increase,  or,  in  other  words,  that  the  secretion  is 
thrown  out  of  equilibrium.    Frequently,  in  the  beginning 
of  disease,  there  is  found  an  abnormally  large  pecentage 
of  fat  that  results  from  the  often  sudden  decrease  of  the 
quantity  of  the  secretion.    A  salty  taste  which  occurs  not 
infrequently,  might  possibly  mean  an  increase  in  the 
quantity  of  protein  and  ash  (secretion  of  blood  serum). 
According  to  long-standing  opinion,  milk  has  an  abnor- 
mal taste  in  cases  of  indigestion  of  all  sorts  and  under 
these  conditions  it  also  curdles  easily. 


VARIATIONS  IN  COW'S  MILK  43 

11.  Medicines.  It  is  an  old  opinion  that  a  number 
of  different  medicines  help  to  increase  the  milk  secre- 
tion and  the  fat  content  of  milk,  and  for  this  reason,  so- 
called  "  milk  powders  "  are  still  used.  The  different 
materials  (fennel,  anise,  caraway,  calamus,  bitters,  sul- 
phur, antimony  compounds,  etc.)  cannot  change  the 
secretion  of  normal  animals,  and  it  is  doubtful  if  they 
are  able  to  recall  the  milk  secretion  after  it  has  been 
checked  through  disease. 

Other  medicines  as  quinine,  belladonna  and  alum,  are 
supposed  to  be  able  to  check  the  secretion  as,  also,  rub- 
bing the  udder  with  opodeldoc,  oil  of  rosemary  and  the 
like ;  but  their  action  is  questionable.  Drugs  like  iodine 
and  phosphorus,  that  act  especially  on  gland  tissue, 
are  able  to  check  the  secretion  or  cause  it  to  stop  alto- 
gether. The  excretion  of  medicines  in  the  milk  will  be 
considered  later. 

Summary.  From  the  above,  it  is  evident  that  the 
gland  cells  of  the  udder  of  each  cow  are  adjusted  to 
secrete  milk  of  a  rather  definite  chemical  composition 
which,  however,  changes  during  the  lactation  period,  but 
that  these  cells  react  to  a  number  of  different  influences 
as  a  result  of  which  they  may  temporarily  secrete  milk 
of  a  somewhat  changed  composition. 

As  would  be  expected,  the  limits  for  the  variations 
in  the  composition  of  cow's  milk  are  reported  differ- 
ently, but  milk  of  a  composition  that  is  not  included  in 
the  limits  below  is  indeed  very  rare. 

Water          Casein         Albumin  Fat  Lactose  Ash 

83—89*       2-5*      0.39— 0.95*      2.5—7.5*      4—5.8*      0.35—1.21* 

It  appears  that  the  fat  content  is  subject  to  great 
variations ;  but,  if  we  leave  out  of  consideration  old 
milking  cows,  these  variations  are  much  less.  The 
quantity  in  milk  of  solids  not  fat  (casein,  albumin,  lac- 


44  MILK  HYGIENE 

tose  and  salts)  is  far  less  variable.  This  applies  espe- 
cially to  lactose,  which  seldom  shows  the  given  mini- 
mum and  maximum  percentage.  In  the  detection  of 
adulterations,  the  percentage  of  lactose  furnishes,  there- 
fore, a  better  guide  than  the  percentage  of  fat. 

By  mixing  the  milk  of  the  members  of  a  herd,  the 
individual  variations  in  composition  are  more  or  less 
equalized,  so  the  composition  of  the  whole  quantity 
approaches  the  average  for  cow's  milk.  There  are, 
however,  some  herds  in  the  milk  of  which  the  percent- 
age of  fat  is  much  higher  than  in  others ;  this  is  a  matter 
of  selection  or  of  breed,  so,  of  course,  the  composition 
of  milk  of  separate  herds  will  not  be  the  same.  As  cows 
usually  calve  at  certain  seasons  the  number  of  fresh 
cows  and  old  milkers  is  not  the  same  at  all  seasons  and, 
for  this  reason,  the  composition  of  the  milk  changes. 
We  have  the  following  figures  showing  the  average  per- 
centage of  fat  as  found  upon  daily  analyses  of  milk 
from  three  large  herds. 

February  May  August  November 

a.  3.18  3.42  3.61            3.47 

b.  3.69  3.56  3.64            3.77 

c.  3.03  3.38  3.51            3.32 

In  herds  a  and  c,  particularly,  calving  is  distributed 
unevenly,  which  causes  the  percentage  of  fat  to  be  0.5 
per  cent,  lower  in  winter  than  in  summer. 

Many  of  the  external  influences  that  have  been  men- 
tioned as  applying  to  the  individual  annual  and  that 
result  in  a  temporary  change  in  the  composition  of  the 
milk,  may  apply,  at  the  same  time,  to  all  of  the  animals 
in  a  herd  and  thereby  influence  the  fat  content  of  the 
herd  milk.  This  is  seen  when  there  is  a  change  of  food, 
disturbance  in  the  stable,  storms,  extreme  heat  and  so 
on.  However,  variations  in  the  composition  of  the  entire 
quantity  of  milk  caused  in  such  ways  are,  in  most  cases, 


CHANGES  IN  THE  SECRETION  45 

less  than  those  of  single  animals,  for  all  members  of 
the  herd  are  not  affected  in  the  same  degree  and  quite 
often  the  animals  react  in  opposite  ways  under  the  same 
circumstances  so  that  these  variations  are,  in  part,  equal- 
ized after  the  milk  has  been  mixed  together.  The  larger 
the  herd,  the  smaller  the  probability  of  all  its  members 
being  influenced  in  the  same  way  at  the  same  time — 
and,  therefore,  the  variations  from  the  normal  will  be 
so  much  less.  For  the  same  reason,  the  variations  are 
considerably  less  when  the  milk  of  several,  but  always 
the  same,  herds,  is  mixed. 

So  far  as  we  know,  there  are  no  data  in  Denmark 
concerning  the  limits  of  the  composition  of  normal  mar- 
ket milk,  and  these  are  not  sufficiently  established  in 
other  places — yet  it  may  be  assumed  that  the  specific 
gravity  does  not  vary  beyond  1.029  to  1.034,  the  content 
of  solids  not  fat  does  not  exceed  8.6  to  8.8  per  cent.,  and 
the  fat  varies  from  2.75  to  3.5  per  cent.5  6 

V.    CHANGES  IN  THE  SECRETION  DURING 
DISEASES  OF  THE  UDDER 

Diseases  of  the  udder  that  cause  material  changes  in 
the  character  and  the  composition  of  the  udder  secretion 
are :  udder  contusion,  udder  redema,  embolism  and 
thrombosis,  mastitis,  udder  tuberculosis,  udder  actino- 
mycosis  and  tumors. 

1.  Contusions  of  the  udder  and  the  teats  which  fre- 
quently are  caused  by  cuffing  and  blows  and  by  kicking 
and  tramping  by  other  cows,  etc.,  produce  haemorrhage 
of  the  udder  tissues,  bloody  serous  infiltration,  or, 
possibly,  death  of  the  udder  tissue.  The  changes  in 

5  Jersey  herds,  etc.,  not  included. 

6  The   figures   given    above   relate    to    Danish    cattle,    practically 
all   of   Avhich   are   of   two   breeds   which   furnish   milk   containing   a 
much    lower   percentage    of   fat   than    is    furnished   by   most   of   the 
herds  producing  market  milk  in  America.      [L.  P.] 


46  MILK  HYGIENE 

the  secretion  consist,  in  part,  of  an  admixture  of  blood 
plasma  that  is  usually  invisible  and,  in  part,  of  blood. 
The  latter  may  appear  in  freshly  drawn  milk  as  drops 
of  blood  or  as  little  clots.  When  more  bleeding  occurs, 
the  milk  is  liable  to  be  diffusely  colored  reddish  and  it 
will  color  the  milk  from  the  other  quarters,  and  even 
colors  the  milk  of  other  cows  reddish  when  mixed  with 
it.  This  admixture  of  blood  cannot  be  proven  by  the 
common  guaiac  method,  for  fresh  milk  will  give  the 
same  reaction.  The  proof  is  most  easily  gained  by 
means  of  microscopic  examination  of  the  sediment 
obtained  by  centrifuging  the  milk,  whereupon  the  red 
blood  corpuscles  are  easily  recognized  among  the  milk 
globules. 

2.  Udder  oedema.    It  may  be  supposed  that  in  udder 
o?dema,  which  frequently  is  very  severe  soon  after  calv- 
ing, there  is  an  admixture  of  transudate  with  the  secre- 
tion, but,  so  far  as  known,  no  investigations  have  been 
made  in  regard  to  this  matter. 

3.  Embolism   and   thrombosis    occur    occasionally   in 
the  udder  and  cause  gangrene  of  a  gland  or  of  a  part  of 
one ;  frequently  there  is  gangrene  of  the  skin  and  of  the 
teat  of  the  quarter  affected.    Milk  secretion  ceases  and 
in  its  place  there  is  a  bloody  serous  exudate. 

4.  Mastitis.    Inflammations  of  the  udder  cause  quite 
characteristic  changes  in  the  secretion,  which  often  stops 
entirely  to  give  place  to  a  purulent  exudate. 

a.  Mucous  catarrh.    When  drawn,  the  milk  contains 
small  yellowish  flakes  and  lumps  which,  upon  standing, 
unite  into  a  slimy,  dirty,  grayish  sediment  or,  together 
with  the  cream,  form  a  lumpy,  dirty  colored  layer  on  the 
top  of  the  milk.    In  severe  attacks  the  secretion  may  be 
viscid,  slimy  and  sticky. 

b.  Purulent  catarrh.    In  the  beginning,  the  secretion 
is  unchanged  but  for  the  presence  of  small  flakes  of  pus 


CHANGES  IN  THE  SECRETION  47 

and  fibrin.  The  milk  secretion  decreases  more  or  less 
quickly  while  the  pus  cells  and  fibrin  increase  in  number 
and,  finally,  the  secretion  is  replaced  by  a  viscid,  whitish 
or  yellowish  purulent  exudate  or  by  a  quantity  of  yel- 
lowish serous  exudate  which  contains  clumps  of  pus  and 
fibrin.  In  many  cases,  the  udder  shrinks  and  the  exuda- 
tion ceases  without  the  return  of  the  milk  secretion ;  in 
other  cases,  milk  secretion  returns  either  during  the 
same  period  of  lactation  or  after  the  birth  of  the  next 
calf.  In  catarrh  of  the  udder,  lactose  decreases  in  quan- 
tity while  the  other  ingredients — except  ash — undergo 
no  quantitative  change  in  the  mildest  cases.  Among  the 
ash  ingredients,  phosphoric  acid,  lime,  magnesia  and 
potash  decrease  materially  in  quantity,  while  sodium 
chloride  occurs  in  more  than  normal  quantity.  In  cases 
when  the  secretion  is  mixed  largely  with  exudate,  the 
quantity  of  lactose  still  further  decreases  and  the  casein 
content  drops,  while  albumin  and  globulin  (also  fibrin) 
increase. 

c.  Parencliymatous  mastitis.     The  changes  in  the 
secretion  correspond  essentially  with  the  changes  in 
purulent  catarrh,  but  they  occur  very  suddenly  and  may 
disappear   as   rapidly.     The  chemical  analysis   shows 
changes  similar  to  those  in  catarrh ;  the  lactose  often  dis- 
appears entirely,  while  the  albumin  and  globulin  in- 
crease greatly  in  quantity.     The  fats  may  increase  or 
decrease,  the  salts  change  as  in  catarrh. 

d.  Gangrenous  mastitis.     The  real  milk  secretion 
ceases  while  a  bloody-serous  liquid  is  secreted  which,  on 
account  of  the  existence  of  bacteria  of  putrefaction,  is 
frequently  mixed  with  gas  and  has  the  odor  of  putre- 
faction. 

The  chemical  changes  that  take  place  in  mastitis 
are  mainly  traced  to  partial  or  entire  cessation  of  the 
real  milk  secretion  and  to  a  simultaneous  elimination  of 


48  MILK  HYGIENE 

an  exudate  having  a  greater  or  less  admixture  of  pus 
cells. 

e.  Udder  tuberculosis.    In  many  cases,  the  secretion 
remains  almost  imperceptibly  changed  for  a  long  period, 
as  only  very  small  flakes  are  intermixed  with  it.    Later 
on,  it  decreases  in  quantity,  grows  thinner  and  contains 
more  flakes,  and,  finally,  it  is  yellowish  or  reddish,  se- 
rous, contains  clumps  and  flakes  and  becomes  more  like 
pus.  Chemically,  the  milk  gradually  undergoes  the  same 
change  as  in  cases  of  other  forms  of  mastitis  (Storch). 

f.  Actinomycosis  and  tumors  of  the  udder  no  doubt 
cause  changes  in  the  appearance  and  the  composition  of 
the  secretion,  but  no  investigations  have  been  made  on 
these  subjects. 

In  mastitis,  tuberculosis  and  actinomycosis  of  the 
udder  pathogenic  bacteria  are  found  in  the  milk;  these 
will  be  discussed  later. 

VI     EXCRETION  OF    FOREIGN  MATTER 
WITH  THE  MILK 

The  milk  glands  may  serve  to  excrete  foreign  mat- 
ter which,  in  some  way,  has  found  entrance  into  the 
organ,  just  as  the  kidneys  and  other  glands  do.  Such 
an  excretion  does  not  take  place  to  as  great  an  extent  as 
was  formerly  believed,  which,  considered  from  a  biologi- 
cal standpoint,  seems  most  natural,  for  the  excretion  of 
foreign  matter  would  prove  a  great  danger  to  the  young 
animal  dependent  on  its  mother's  milk  for  food.  Yet 
there  are  not  a  few,  and  sometimes  very  harmful,  sub- 
stances that  are  excreted  from  the  organism  through  the 
udder  and,  therefore,  it  is  one  of  the  problems  of  milk 
hygiene  to  prevent  the  milk  of  such  cows  as  are  affected 
in  this  way,  from  being  used,  just  as  the  physician  must 
always  consider,  in  the  treatment  of  mothers  and  wet 
nurses,  what  influence  medicines  to  be  given  may  have 
on  the  nursing  child. 


EXCRETION    OF    FOREIGN    MATTER       49 

Reports  differ  as  to  what  foreign  substances  are 
excreted  with  the  milk.  These  differences  of  opinion 
may  be  accounted  for  in  part  by  the  fact  that  many  sub- 
stances are  not  excreted  in  noticeable  quantity  until  the 
animal  has  taken  relatively  large  amounts  of  them. 
Sometimes  individual  peculiarities  operate,  for  it  may 
be  that  some  inflammation  not  entirely  healed,  local 
induration  or  similar  changes  in  the  tissues  of  the  udder, 
in  short,  the  injuries  that  remain  after  mammitis,  favor 
such  an  excretion. 

It  has  been  mentioned  before  that  the  milk  contains 
only  traces  of  iron,  and  this  fact  alone  is  a  proof  that 
iron  compounds  are  not  usually  excreted  with  the  milk; 
even  after  the  consumption  of  a  great  quantity  of  iron 
during  a  long  time,  the  iron  content  does  not  rise.  Con- 
cerning other  metals,  compounds  of  copper,  lead  and 
antimony7  are  excreted  only  in  very  small  quantity,  so 
that  even  a  prolonged  adminstration  of  these  substances 
to  milch  cows  usually  brings  about  no  harmful  effects. 
According  to  investigations  by  Baum  and  Seeliger,  the 
lead  content  of  milk  does  not  increase  beyond  0.0009  to 
0.002  per  cent.,  even  after  treating  cows  with  large  doses, 
and  this  quantity  is  without  importance,  even  to  quite 
small  children. 

On  the  other  hand,  mercury  is  easily  excreted 
through  the  udder,  when  this  substance  is  taken  through 
the  digestive  organs  or  when  absorbed  after  applications 
to  the  skin.  Iodine  and  arsenic  also  easily  enter  the  milk 
in  considerable  quantity. 

Opinions  differ  concerning  alkaloids.  It  is  a  fact, 
however,  that  morphine,  strychnine,  atropine  and  vera- 
trin  are,  under  certain  circumstances,  excreted  with  the 

7  In  the  older  literature,  there  are  recorded  a  number  of  observa- 
tions which   indicate   that   tartar  emetic  may  be  excreted  with   the 
milk  in   large  quantity 
4 


50  MILK  HYGIENE 

milk  in  such  large  quantities  as  to  be  dangerous  to  chil- 
dren. Other  substances  which  can  easily  be  excreted 
with  milk  are  salicylic  acid,  carbolic  acid,  aloes,  croton 
oil  and  senna,  also  the  active  principles  of  colchicum, 
hyoscyamus  and  euphorbium.  This  is  also  supposed  to 
be  the  case  with  mustard;  still  there  is  good  reason  to 
believe  that  it  is  true  only  if  mustard  is  taken  with  the 
food  in  large  quantities. 

It  has  often  been  observed  that  diarrhoea  occurs  in 
people  who  have  used  the  milk  of  cows  fed  upon  food 
that  is  moulded,  or  that  has  undergone  putrefactive 
fermentation.  It  is  presumed,  therefore,  that  some  of 
the  substances  which  are  formed  under  these  conditions 
in  the  food  materials  of  the  cow  may  be  excreted  with 
the  milk.  But  it  is  possible  that  in  such  cases  there  is 
contamination  of  the  milk  from  the  food  during  milking 
and  so,  in  this  way,  bacterial  changes  may  occur ;  these 
have  not  been  entirely  excluded. 

It  was  stated  above  that  aromatic  substances  in  for- 
age plants  are  apparently  excreted  in  slight  quantity 
and  may  give  a  ' '  taste ' '  to  the  milk.  [The  garlicky  taste 
that  is  so  common  in  milk  in  the  Spring  in  the  Eastern 
United  States  is  due  to  garlic  in  the  pastures.]  We  find, 
too,  that  strongly  smelling  medicines  (asafcetida,  ether, 
certain  volatile  oils,  but  not  all)  that  are  given  to  the 
cows  may  impart  a  taste  to  the  milk. 

It  is  highly  probable  that  toxic  substances  which  are 
formed  in  the  organism  during  disease,  and  also  such 
substances  that,  for  example,  are  reabsorbed  from  the 
uterus,  may  sometimes  be  excreted  in  the  milk,  but  there 
is  no  definite  information  on  this  subject.  On  the  other 
hand,  we  know  that  antitoxins  are  in  part  eliminated 
from  the  blood  of  the  mother  animal  through  the  udder 
and,  through  this  channel,  they  may  be  used  by  the  young 
to  its  benefit. 


CHANGES  IN  MILK  51 

VII.    CHANGES  IN  MILK  CAUSED  BY 
MICRO-ORGANISMS 

Milk  found  in  the  glandular  passages  and  cisterns  of 
the  healthy  udder  is  usually  sterile.  On  the  other  hand, 
the  ducts  of  the  teats  and,  still  more,  the  ends  of  the 
teats  usually  contain  bacteria  and,  therefore,  the  milk 
when  drawn  is  infected  with  them.  This  is  more  apt  to 
be  the  case  when  the  milk  comes  in  contact  with  the 
hands  of  the  milkers,  or  when  it  is  poured  into  the  not 
always  sterile  bucket,  or  when  particles  of  dirt  and  dust 
from  the  udder  or  the  skin  of  the  cow,  from  the  clothing 
of  the  milkers  or  from  the  air,  drop  into  the  milk. 
Before  the  milking  is  finished,  a  considerable  number  of 
different  bacteria  have  been  added  to  the  milk  and 
though,  for  a  time,  it  has  bactericidal  properties,  that 
is,  it  is  able  to  kill  bacteria  or,  at  least,  to  prevent  their 
growth,  yet  the  number  of  bacteria  does  not  diminish 
noticeably  but,  in  the  course  of  time,  increases  enor- 
mously. Shortly  after  milking,  thousands,  even  hun- 
dreds of  thousands,  of  bacteria  may  be  found  in  each 
cubic  centimetre. 

In  inflammatory  processes,  catarrh,  tuberculosis  and 
actinomycosis  of  the  udder,  infected  wounds  at  the  open- 
ing of  the  teat,  etc.,  bacteria  are  more  or  less  numerous 
in  the  milk  before  it  is  drawn.  In  benign  udder  inflam- 
mations bacteria  disappear  almost  entirely  with  the 
cessation  of  the  disease,  but  occasionally  it  happens  that 
the  bacterial  growth  continues  for  a  time  in  the  milk 
contained  in  the  glandular  passages,  after  the  secretion 
has  become  apparently  quite  normal  and  after  all  signs 
of  inflammation  have  disappeared. 

In  general  infections,  not  localized  in  the  udder,  as 
a  rule  no  microbes  are  excreted  with  the  milk.  An  excep- 
tion to  this  is  foot-and-mouth  disease  (aphthous  fever), 
in  which  the  milk  of  the  affected  cows  often  contains  vir- 


52  MILK  HYGIENE 

ulent  material,  the  nature  of  which  is  not  definitely 
established.  During  this  disease,  several  noticeable 
changes  occur  in  the  milk  and  it  is,  therefore,  very  prob- 
able that  pathological  processes  take  place  in  the  cells 
of  the  gland  and  so  an  excretion  of  virus  is  only  to  be 
expected.  In  other  acute  diseases,  as  anthrax,  hemor- 
rhages may  occur  in  the  tissues  of  the  udder  and  the 
admixture  of  bacteria  from  the  blood  follows  naturally. 
The  changes  in  the  milk  caused  by  microbes,  and  par- 
ticularly by  bacteria,  which  comprise  by  far  the  greatest 
number  of  micro-organisms  of  milk,  are  very  numerous. 
These  are  most  readily  studied  by  working  with  sterile 
milk  (the  best  way  is  to  use  milk  which  was  taken  from 
the  udder  in  sterile  condition,  for  milk  undergoes  quite 
essential  changes  when  heated)  and  with  pure  cultures 
of  bacteria.  The  most  important  changes  are  the 
following : 

a.  The    milk    is    unchanged    in    appearance,    reaction, 
odor  and  taste  in  spite  of  bacterial  growth. 

b.  The    bacteria    form    alkali    (probably    ammonia) ; 
the  reaction  grows  more  and  more  alkaline  and  when, 
after  some  time,  a  certain  alkalinity  is  reached,  the  fat 
is  saponified,  the  neutral  casein-lime  compound  becomes 
a  base  and,  as  a  result  of  this,  the  milk  is  changed  to  a 
yellowish  translucent,  whey-like  liquid. 

c.  The  bacteria  split  up  the  lactose,  forming  acid. 
The  main  product  of  this  division  is  lactic  acid,  some- 
times d-lactic  acid,  sometimes  1-lactic  acid,  sometimes  a 
mixture  of  both,  i-lactic  acid.  The  reaction  may  be  ex- 
pressed by  this  formula:  C12H22O11+H20=4(C,H603). 
In  fact,  however,  this  process  is  far  more  complicated 
for  beside  the  lactic  acids,  a  number  of  other  com- 
pounds are  formed  in  small  quantity  as  by-products : 
alcohol,  valeric  acid,  acetic  acid,  succinic  acid,  carbonic 
acid,  etc.  After  a  certain  amount  of  free  lactic  acid  has 


CHANGES  IN  MILK  53 

been  formed,  coagulation  of  the  casein  occurs — at  room 
temperature — which  either  is  precipitated  as  flakes  or 
thickens  to  a  firm,  jelly-like  substance  (curdling  of 
milk)  and  frequently  contains  small  gas  bubbles.  At  a 
higher  temperature,  coagulation  occurs  in  the  presence 
of  a  smaller  percentage  of  acid.  If  coagulation  is  caused 
by  acid  alone,  the  process  unquestionably  is  a  simple 
separation  of  the  casein-lime  compound  by  which  the 
casein,  insoluble  in  water,  is  precipitated  unchanged. 
When  the  casein  is  filtered  out  and  treated  with  lime 
water,  it  dissolves  readily.  In  heating  sour  milk  to  70° 
C.  and  above,  a  real  coagulation  will  occur,  however,  and 
the  precipitated  casein  cannot  be  dissolved  in  lime  water. 
After  the  formation  of  lactic  acid  has  reached  a  cer- 
tain degree  (about  0.8  per  cent.,  which  corresponds  to 
an  amount  of  acid  in  100  c.c.  of  milk  that  requires  for  its 
neutralization  about  100  c.c.  of  a  one-tenth  normal  solu- 
tion of  Na20),  the  activity  of  the  bacteria  ceases,  for 
they  cannot  thrive  in  the  strongly  acid  liquid,  and  the 
greater  number  of  bacteria  rather  quickly  perish.  The 
different  bacteria  and  yeast  fungi  which  may  be  the 
cause  of  lactic  acid  fermentation,  are  not  sensitive  to  the 
same  degree  of  acidity,  and  under  the  influence  of  these 
various  forms,  the  milk  becomes  sour  irregularly.  These 
various  organisms  are  influenced  very  largely  by  exter- 
nal conditions,  in  respect  to  their  ability  to  produce 
lactic  acid,  so  that  sometimes  a  longer  and  sometimes  a 
shorter  time  is  required  to  sour  milk,  while,  in  other 
cases,  their  ability  to  produce  this  change  is  almost  lost. 
Of  the  micro-organisms  which  can  produce  a  lactic  acid 
fermentation,  are  to  be  considered  the  lactic  acid  bacte- 
ria used  in  creameries  (a  group,  the  various  species  of 
which  have  not  been  definitely  differentiated),  certain 
yeast-like  fungi  (Saccharomyces  lactis  and  Saccharo- 
myces  acidi  lactici)  the  Bacillus  coll  communis,  strep- 


54  MILK  HYGIENE 

tococci  and  the  pyogenic  staphylococci.  Some  of  these, 
in  addition  to  producing  an  acid,  develop  a  ferment 
which  has  an  action  somewhat  similar  to  that  of  rennet 
(see  below). 

d.  Bacteria  may  form  a  rennet-like  ferment  which 
causes  the  milk  to  form  a  coagulum  of  the  consistency  of 
jelly,  without  souring.  The  ferment,  which  can  be  iso- 
lated comparatively  easily  from  many  bacteria,  has 
effect  in  the  same  manner  and  under  similar  conditions 
as  chymosin.  The  precipitated  casein  cannot  be  dis- 
solved again  by  treatment  with  diluted  lime  water,  and 
it  may  be  assumed  that  the  ferment  has  produced  a 
change  of  the  casein  into  paracasein,  whose  compound 
with  lime  is  not  soluble,  as  is  well  known.  A  great 
number  of  bacteria  are  known  which  change  the  milk  in 
this  manner;  for  example,  forms  that  belong  to  the 
typhoid-colon  group,  many  bacilli  that  are  included  in 
the  large  group  of  spore-bearing  hay  bacilli,  among 
them  those  named  by  Duclaux,  Tyrothrix  tennis,  scaber, 
filiformis,  etc.  Bacilli  belonging  to  this  last  group  are 
often  found  in  milk,  because  they  are  usually  frequent 
in  the  soil  and  dust  and  in  the  excrement  of  the 
cattle,  so  that  they  always  find  their  way  into  the  milk 
when  it  is  drawn.  The  bacteria  under  consideration 
have  different  influences  on  the  milk.  While  some, 
apparently,  only  cause  the  milk  to  curdle  (they  also 
separate,  at  the  same  time,  small  quantities  of  albumose- 
like  substances — probably  caseoses  and  peptone),  others 
are  able  to  redissolve  the  casein  curd  by  means  of  a 
peptonizing  ferment  ("  casease  ") — and  thus  increase 
the  quantity  of  caseoses.  Still  others  not  only  dissolve 
the  curd,  but  also  break  up  the  molecule  of  albumin,  so 
that  in  the  fluid  such  products  appear  as  peptone,  leu- 
cm,  tyrosin,  ammonia,  butyric  acid,  etc.  Sometimes  the 
development  of  butyric  acid  is  so  considerable  that  it 


CHANGES  IN  MILK  55 

causes  the  cultures  to  stink  (butyric  acid  fermentation). 
Finally,  the  milk  is  changed  into  a  watery  mixture 
which  contains  some  fat  lumps  and  has  a  more  or  less 
disagreeable  odor. 

e.  Bacteria  cause  coagulation  of  milk  partly  by  the 
production  of  acid  and  partly  by  the  action  of  ferments. 
Many  bacteria  as,  for  example,  certain  lactic  acid 
bacteria  and  some  members  of  the  colon  group,  coagulate 
milk  through  the  production  of  acid.  The  precipitated 
casein  is,  however,  insoluble  in  diluted  lime  water,  which 
is  an  indication  that  it  has  been  changed,  by  the  action  of 
ferments,  into  paracasein. 

/.  Bacteria  may  produce  a  slimy  condition  in  milk  or 
in  cream.  In  this  condition,  these  fluids  become  thick 
and  their  consistency  is  so  great  that  long  strings  may 
be  drawn  out.  The  milk  may,  at  the  same  time,  become 
acid,  although  usually  this  is  not  the  case.  There  are 
many  bacteria  of  different  kinds  that  are  capable  of 
causing  this  change.  In  some  cases,  the  sticky  condition 
comes  from  the  rapid  swelling  of  the  slimy  capsules  of 
the  bacteria,  while  in  other  cases  the  change  is  thought 
to  be  due  to  unidentified  changes  in  some  constituents  of 
the  milk,  presumably  the  lactose.  It  has  been  thought 
that  this  slimy  condition  may  be  caused  by  feeding  a 
certain  plant,  Pinguicula  vulgaris,  in  the  same  manner 
that  placing  the  leaves  of  this  plant  in  milk  may  produce 
the  change. 

Jonsson  has  found  that  there  are  bacteria  on  the 
leaves  of  this  plant  that  make  milk  slimy  or  stringy, 
therefore  it  is,  no  doubt,  safe  to  conclude  that  feeding 
with  this  plant  is  without  special  significance  in  this 
particular.  Stringy  milk  is  not  unwholesome ;  in  north- 
ern Sweden  it  is  eaten  in  the  same  manner  as  coagulated 
milk  is  used  elsewhere. 

g.    Bacteria  may  cause   abnormal   odors   and  tastes   in 


56  MILK  HYGIENE 

milk  without  producing  an  alteration  in  appearance  or 
any  of  the  changes  above  noted. 

The  Bacillus  fcetidus  lactis  described  by  Jensen  is 
one  of  the  colon  group  which  has  the  property  of  pro- 
ducing in  milk  an  unpleasant  odor  similar  to  the  odor 
of  turnips,  and  also  a  corresponding  sweetish,  bitter,  re- 
pulsive taste.  This  organism,  and  closely  related  forms, 
are  probably  the  real  causes  of  the  so-called  turnip  taste 
of  milk.  Various  micrococci  and  bacilli  are  capable  of 
producing  a  very  strong  bitter  taste  without  altering  the 
milk  in  other  respects.  This  change  is  sometimes  due  to 
the  ^production  of  peptone  and,  no  doubt,  to  the 
elaboration  of  other  compounds. 

Jensen  has  described  a  small  bacterium  that  pro- 
duces in  milk  an  exceedingly  strong  burnt  taste  and 
odor,  that  resembles  the  odor  and  taste  of  malt.  This 
was  so  strong  as  to  cause  a  malty  odor  throughout  an 
infected  creamery.  It  may  be  that  this  bacterium  is  the 
real  cause  of  the  so-called  "  malty  taste  "  of  milk  and 
butter.  Another  organism — a  micrococcus — was  found 
to  give  milk  an  unpleasant  fatty,  burnt  taste. 

A  bacillus  studied  by  Veigman  and  Zorn  produces  an 
unpleasant  soapy  taste,  while  a  bacterium  mentioned 
by  Storch  gives  rise  to  an  oily  taste  in  coagulated  milk. 
Other  bacteria  cause  other  less  clearly  marked  tastes 
and  odors  that  cannot  be  more  definitely  characterized 
than  as  unclean. 

Jl.  Bacteria  may  cause  abnormal  coloration  of  milk; 
the  most  important  abnormalities  of  this  class  are : 

Blue  milk  is  caused  by  the  Pseudomonas  syncyanea 
(Bacillus  cyano genus),  which  produces  a  grayish  color 
on  the  surface  of  milk,  while  in  sour  milk  distinct  blue 
spots  appear,  that  may  become  confluent. 

Red  milk.  Certain  bacteria,  as  the  Bacillus  prodigio- 
sus  and  the  Sarcina  rosacea,  grow  on  the  surface  of  milk, 


CHANGES  IN  MILK  57 

producing  a  red  color  partly  as  spots  and  partly  as  a 
diffuse  discoloration  covering  the  entire  surface.  The 
Bacterium  lactis  ery  thro  genes,  isolated  by  Grotenfeldt, 
coagulates  milk  and  afterwards  dissolves  the  coagulum 
into  a  red  fluid. 

Yellow  milk  is  produced  by  a  number  of  organisms 
that  cause  the  development  of  yellow  or  orange-colored 
spots  on  the  surface.  Bacillus  synxanthus  is  an  exam- 
ple of  these  organisms  that  are  derived  from  the 
atmosphere. 

Summary.  Milk  that  is  not  sterile  and  that  is  left 
to  itself,  usually  undergoes  lactic  acid  fermentation  for 
the  reason  that  lactic  acid  bacteria  are  present  in  large 
numbers,  and  by  breaking  up  the  milk  sugar  to  form 
acid,  most  of  the  other  forms  of  bacteria  are  repressed 
to  a  high  degree.  Curdled  milk  may  have  a  clean,  sour 
taste,  or  a  more  or  less  unpleasant,  bitter,  offensive  or 
oily  taste.  The  latter  condition  comes  from  either 
simultaneous  development  of  other  bacteria  or  from  the 
peculiar  effects  of  special  lactic  acid  bacteria  which  have 
caused  the  acid  formation.  Coagulated  milk  left  to  itself 
is  usually  quickly  covered  with  a  thin,  whitish,  consist- 
ent layer  formed  of  milk  moulds  (Oidium  lactis}  and, 
not  infrequently,  colored  spots  appear  that  are  caused 
by  bacteria  or  fungi,  as  Penicillium  glaucum.  By 
degrees  the  coagulated  milk  undergoes  a  putrefactive 
transformation  accompanied  by  a  foul-smelling  disin- 
tegration of  the  casein. 

Less  frequently,  the  milk  quickly  becomes  slimy  or 
stringy  before  it  has  become  acid,  or  while  it  is  begin- 
ning to  sour.  Or  it  may  early  acquire  a  bitter  taste 
and  an  unpleasant,  loathsome  odor;  very  often  it  does 
not  sour  and  coagulate,  but  gradually  putrefies:  the 
usual  lactic  acid  fermentation  has  not  appeared  and 
checked  the  increase  of  the  bacteria  of  putrefaction. 


58  MILK  HYGIENE 

It  sometimes  happens  that  milk  coagulates  quickly 
without  souring;  the  coagulum  is  quite  firm,  the  taste 
sweetish,  often  slightly  unpleasant.  In  this  case,  the 
lactic  acid  fermentation  has  ceased,  while  the  bacteria 
referred  to  in  paragraph  d  have  grown  freely.  Left 
to  itself,  such  milk  will  quickly  become  putrid. 

VIII.  CHANGES  IN  MILK  AT  HIGH  TEMPERATURES 

When  milk  is  boiled  in  an  open  vessel,  it  becomes 
covered  with  a  coating  of  coagulated  casein ;  after  this  is 
removed,  a  new  membrane  is  immediately  formed.  If 
the  milk  is  constantly  stirred,  the  membrane  is  not 
formed.  The  origin  of  this  coating  is  not  entirely  clear, 
but  it  is  possible  that  it  comes  from  a  partial  drying  of 
a  superficial  layer  of  milk. 

Viscosity  is  diminished  upon  boiling  or  long  pasteur- 
ization, so  that  boiled  milk  appears  to  be  thinner  than 
raw  milk.  This  is  expressed  by  Babcock  by  the  fol- 
lowing figures  relating  to  two  samples  of  milk  tested : 
265  raw,  and  250  pasteurized;  275  raw,  and  257  boiled. 
The  specific  gravity  of  milk  changes  so  little  upon  heat- 
ing as  to  be  practically  of  no  account. 

Lactose  is  not  changed  when  simply  boiled,  but  heat- 
ing at  a  higher  temperature  causes  a  burnt  condition 
(caramel  formation)  and  partial  separation  into  lactic 
acid,  causing  the  milk  to  become  slightly  acid. 

Albumin  and  globulin  coagulate  upon  heating  the 
milk  for  a  short  time  to  70°  to  80°  C.,  and  it  is  probable 
that  casein  also  undergoes  a  change,  but  it  has  scarcely 
any  significance  and  has  been  studied  but  little  up  to 
this  time.  But  if  milk  possesses  a  certain  degree  of 
acidity,  heating  causes  coagulation  of  the  casein.  Boiled 
milk  is  not  influenced  at  all,  or  only  very  slightly,  by 
rennet  ferment;  the  reason  for  this  is  not  to  be  found 
in  change  in  the  casein,  but  lies  in  the  partial  transfer- 


CHANGES  IN  MILK  59 

mation  and  separation  of  the  calcium  phosphate,  as 
discussed  below. 

A  number  of  investigations  have  been  conducted  to 
determine  whether  or  not  casein,  when  boiled,  undergoes 
a  change  in  respect  to  digestibility ;  although  the  results 
do  not  wholly  agree,  such  a  change  does  not  appear 
to  take  place. 

Pasteurization  and  boiling  cause  no  material  change 
in  the  fats  of  milk;  the  number  of  the  globules  is  not 
reduced,  there  is  no  fusing  of  the  globules.  Possibly 
the  quantity  of  volatile  acids  decreases,  but  no  investi- 
gations have  been  made  on  this  subject. 

The  salts  of  milk  undergo  a  change  upon  heating,  as 
the  soluble  calcium  salts  become,  in  part,  insoluble  phos- 
phate of  lime,  especially  tricalcium  phosphate,  Ca3P208. 

As  already  mentioned,  there  is  much  reason  to 
believe  that  fresh  milk  contains  a  peptonizing  ferment, 
galactase;  if  this  is  the  case,  boiling  or  simply  pasteur- 
izing must,  of  course,  destroy  it.  This  also  destroys 
antitoxins  that  may  be  in  milk.  It  is  also  safe  to  say 
that  toxic  substances  which  result  from  diseases  of  the 
cow  or  come  from  bacterial  growth  in  milk,  are  made 
at  least  partially  harmless  by  continued  boiling. 

It  is  a  well-known  fact  that  the  taste  and  odor  of 
milk  are  changed  by  boiling;  the  "  boiled  taste  "  ap- 
pears when  it  is  heated  to  from  80°  to  85°  C.,  but  this 
is  less  strong  than  that  produced  at  a  higher  tempera- 
ture and  is  considerably  lessened  by  prompt  cooling, 
immediately  after  heating.  It  also  appears  that  the 
"  boiled  taste  "  is  less  marked  when  the  milk  is  heated 
in  a  closed  vessel,  so  that  the  absorbed  carbonic  acid 
gas  may  not  escape,  or  when  the  milk  is  boiled  in  the 
presence  of  carbonic  acid  gas. 

The  action  that  pasteurization  and  boiling  have  upon 
bacterial  growth  in  milk  will  be  taken  up  later. 


PART   III. 


HARMFUL  PROPERTIES  WHICH  MILK 
MAY  POSSESS. 

UNDER  certain  conditions,  milk  may  possess  harm- 
ful properties.  When  the  cow  is  diseased,  poisonous 
substances  may  occur  in  the  milk,  and  the  composi- 
tion of  the  milk  may  differ  widely  from  normal;  in 
udder  infections,  milk  contains  an  admixture  of  patho- 
genic bacteria,  and  such  contaminations  may  also  occur 
during  or  after  milking.  Milk  may  also  take  on  injuri- 
ous properties  through  the  action  of  saprophytic  organ- 
isms and  through  accidental  or  intentional  additions  of 
harmful  substances,  as  preservatives.  While,  in  some 
cases,  there  is  only  an  altered  appearance,  taste  or  odor 
that  serves  to  make  the  milk  unappetizing  and  to  cause 
nausea  or,  perhaps,  vomiting,  in  other  cases  the  milk 
may  be  decidedly  injurious  and  cause,  under  certain 
conditions,  serious  illness,  even  an  epidemic. 

I.    EXCRETION  OF  POISONOUS  SUBSTANCES 
WITH  MILK 

It  has  been  stated  that  different  foreign  materials 
may  be  excreted  through  the  udder  tissue.  This  applies 
principally  to  mercury,  preparations  of  arsenic,  various 
alkalies,  iodine,  irritant  substances  (euphorbium,  etc.) 
and  certain  volatile  oils.  Although  these  substances  are 
not  often  present  in  great  quantities,  yet  milk  may  be 
flavored  by  them,  and  in  this  case  it  may  be  dangerous 
for  small  children  and  weak  persons.  Since  it  is  safe 
to  affirm  that  many  materials  that  are  not  usually 

60 


ADDITION  OF  ANTISEPTICS  61 

excreted  through  the  udder  may  be  excreted  under  cer- 
tain conditions,-  and  by  some  cows,  it  will  be  wise  to 
regard  as  suspicious  all  milk  from  cows  that  are  treated 
medically  with  remedies  that  are  toxic,  and  to  forbid  its 
sale  for  human  food. 

Further,  since  it  is  quite  probable  that  toxic  sub- 
stances formed  in  the  organism  during  the  course  of 
acute  infectious  diseases  may  be  excreted  through  the 
udder,  there  is  good  reason,  also,  to  prevent  the  use  of 
milk  of  such  animals. 

II.    ADDITION  OF  ANTISEPTICS   (PRESERVATIVES) 

The  addition  of  antiseptics  is  frequently  undertaken 
by  dealers,  in  order  to  increase  the  keeping  quality  of 
milk.  In  some  places  the  addition  of  preservatives  is 
very  common  and  quite  a  number  of  antiseptics  are 
used.  As  most  antiseptics  are  harmful  not  only  to  the 
lower  fungi,  but  also  to  the  cells  of  the  higher  animals, 
and  are  to  .be  considered  as  poisons  for  animals  and 
man,  it  is  self-evident  that  the  addition  of  antiseptics 
should  be  undertaken  with  great  care  or,  much  better, 
omitted  altogether.  In  this  connection,  it  must  be  kept 
in  mind  that  one  person  may  be  peculiarly  affected  by 
substances  that  have  no  effect  on  another,  and  that  even 
a  small  addition  of  an  antiseptic  may  be  harmful  to 
'some  people. 

The  addition  of  antiseptics  prevents  acidulation  and 
coagulation,  and  so  may  conceal  the  fact  that  the  milk 
is  already  half  spoiled.  Some  substances,  in  very  slight 
quantity,  directly  prevent  the  increase  of  acid-forming 
bacteria,  and  so,  indirectly,  they  may  promote  the 
growth  of  the  more  resistant  bacteria  of  putrefaction. 

In  most  countries  the  addition  of  antiseptics  to  milk 
and  other  foods  is  prohibited  by  law. 

The  preservatives  most  used  are:  boric  acid,  sali- 


62  MILK  HYGIENE 

cylic  acid,  benzole  acid,  potassium  bicromate  and  for- 
malin. Barely,  peroxide  of  hydrogen  and  fluorides  are 
used. 

a.  Boric  acid  is  sometimes  used  as  such,  sometimes 
as  borax,  and  is  able,  when  added  in  the  proportion  of 
0.1  per  cent,  to  0.2  per  cent.,  to  prevent  bacterial  growth 
for  several  days  so  that  coagulation  does  not  take  place. 
It  is  said  that  boric  acid  is  a  harmless  substance,  and  it 
is  true  that  it  has  been  used  as  medicine  in  quite  large 
doses  without  injurious  effect  being  perceived.  On  the 
other  hand,  observations  and  investigations  have  been 
made  which  fully  prove  that  boric  acid  may  cause 
illness,  vomiting  and  diarrhoea,  and  if  given  for  a 
prolonged  time,  may  injure  the  kidneys  and  cause  some- 
what rapid  and  not  inconsiderable  loss  of  weight;  the 
latter  depends  partly  on  the  fact  that  the  food  is  not  well 
assimilated  and  partly  on  the  increase  of  metabolism 
(Rubner).  Experiments  on  animals  have  confirmed  the 
results  of  these  investigations  and,  indeed,  demonstrate 
that  boric  acid  may  even  cause  a  fatal  poisoning;  for 
example,  Annett  fed  five  kids  with  milk  that  was  mixed 
with  1  gr.  boric  acid  to  the  litre;  all  five  died  in  the 
course  of  2  to  4  weeks.  It  may  be  said,  further,  that 
boric  acid  is  excreted  from  the  organism  slowly  so  that 
the  toxic  effect  is  not  temporary  and  transitory,  so  boric 
acid  must  be  considered  to  be  an  injurious  substance  and 
its  addition  to  milk  and  other  food  is  to  be  forbidden. 

Boric  acid  may  be  detected  in  milk  in  different  ways : 

According  to  Villiers  and  Fayolle,  milk  is  evaporated 
to  dryness  and  ignited,  the  ash  is  wet  with  sulphuric  acid, 
3  c.c.  methyl  alcohol  is  added  and  the  solution  is  distilled 
until  sulphuric  acid  vapor  begins  to  appear.  The  vapor 
is  ignited  and  if  boric  acid  be  present,  in  even  a  very 
small  quantity,  this  will  burn  with  a  green  flame. 

Meissl  recommends  the  following  method:  100  c.c.  of 


ADDITION  OF  ANTISEPTICS  63 

milk  are  mixed  with  milk  of  lime,  evaporated  and 
ignited ;  the  ash  is  dissolved  in  a  very  little  concentrated 
hydrochloric  acid;  the  carbon  is  filtered  out,  the  filtrate 
is  made  slightly  alkaline  and  evaporated  to  dryness. 
This  salt  is  treated  with  a  little  turmeric  tincture  and 
with  some  very  dilute  sulphuric  acid  and  is  evaporated 
in  a  water  bath.  If  boric  acid  is  present,  the  mass  is 
colored  a  distinct  cherry  red. 

[Leffmann8  gives  the  following  method:  "A  few 
drops  of  the  sample  are  mixed  with  a  drop  of  hydro- 
chloric acid  and  a  drop  of  strong  alcoholic  solution  of 
turmeric,  evaporated  to  dryness  at  a  gentle  heat,  and  a 
drop  of  ammonium  hydroxide  added  to  the  residue  when 
cold.  A  dull  green  stain  shows  that  boric  acid  is  pres- 
ent." 

Richmond  9  offers  this  method :  "  To  a  little  milk  add 
a  few  drops  of  phenolphthalein,  and  sodium  hydroxide 
solution,  drop  by  drop,  till  a  faint  pink  color  is  pro- 
duced; place  some  of  the  milk  in  two  test  tubes,  dilute 
one  with  an  equal  volume  of  water,  and  the  other  with  a 
neutral  50  per  cent,  solution  of  glycerin ;  in  the  absence 
of  boric  acid  the  two  tubes  will  have  almost  the  same 
color,  in  its  presence  the  glycerin  tube  will  be  the 
lighter,  and  usually  white."  L.P.] 

b.  Salicylic  acid  in  a  quantity  equivalent  to  0.04  per 
cent,  can  prevent  the  souring  of  milk  for  36  hours,  even 
when  the  milk  remains  at  18°  C.  It  is  very  hard  to 
dissolve  and  has  not  been  extensively  used  to  preserve 
milk. 

Salicylic  acid  has  the  effect  of  checking  digestion  and, 
with  some  persons,  it  may  cause  irritation  of  the  kid- 
neys; particularly  for  children,  salicylic  acid  should  be 


8  Analysis  of  Milk  and  Milk  Products. 

9  Laboratory  Book  of  Dairy  Analysis. 


64 .  MILK  HYGIENE 

considered  injurious.  On  this  account  its  use  should  be 
prohibited. 

The  presence  of  salicylic  acid  in  milk  is  determined 
in  the  following  ways  : 

To  20  c.c.  of  milk  add  2  to  3  drops  of  sulphuric  acid 
and  about  the  same  amount  of  ether,  then  shake  the 
mixture.  The  ether  dissolves  the  fats  and  the  salicylic 
acid  that  is  present.  The  ether  solution  is  evaporated 
and  the  residue  is  extracted  with  40  per  cent,  solution  of 
alcohol  and  filtered.  The  addition  of  a  few  drops  of 
ferric  chloride  solution  to  the  filtrate  gives  a  violet  color 
if  salicylic  acid  be  present.  (Remont.) 

Girard  mixes  100  parts  milk  with  100  parts  water  at 
60°  C.,  and  then  adds  a  few  drops  of  acetic  acid  and  a 
few  drops  of  a  solution  of  mercuric  nitrate,  the  mixture 
is  then  shaken  vigorously  and  filtered.  The  filtrate  is 
shaken  with  ether,  which  dissolves  the  salicylic  acid. 
The  ether  layer  is  then  filtered  and  is  evaporated  in  the 
air;  if  salicylic  acid  be  present  it  remains  behind  as  a 
white  crystalline  mass,  which,  after  solution  in  alcohol, 
is  colored  violet  by  a  weak  solution  of  ferric  chloride. 

c.  Benzoic  acid  possesses  very  powerful  antiseptic 
properties,  but  is  difficult  of  solution,  and  is  little  used 
as  a  preservative  of  milk.  Benzoic  acid  appears  to  be 
somewhat  harmful  to  man,  and  may  be  poisonous  in 
large  doses;  there  is  little  definite  knowledge  as  to  its 
special  effect  on  young  children. 

The  tests  for  benzoic  acid  in  milk  are  more  compli- 
cated. 400  c.c.  to  500  c.c.  of  milk  is  made  alkaline  by 
the  addition  of  lime  water  and  evaporated  to  about 
one-fourth  its  volume ;  this  is  then  mixed  with  pulverized 
pumice  stone  until  it  forms  a  thick  pap,  which  is  evap- 
orated to  dryness  over  a  water  bath.  The  mass  is  pul- 
verized, moistened  with  diluted  sulphuric  acid  and 
shaken  with  a  double  quantity  of  50  per  cent,  alcohol. 


ADDITION  OF  ANTISEPTICS  65 

The  alcoholic  liquid  is  neutralized  with  baryta  water 
and  evaporated  to  about  10  c.c.  Dilute  sulphuric  acid  is 
again  added  and  the  liquid  is  shaken  3  or  4  times  with  a 
little  ether,  which  is  collected  each  time  with  a  pipette. 
The  ether  is  evaporated  and  the  benzoic  acid  remains  in 
almost  pure  condition.  The  mass  is  dissolved  in  a  little 
warm  water  and  a  drop  of  a  solution  of  sodium  acetate 
and  a  drop  of  a  neutral  solution  of  ferric  chloride  are 
added.  If  benzoic  acid  be  present,  a  reddish  sediment 
of  benzoate  ferric  oxide  appears  (Meissl) ;  or  a  little  of 
the  dried  mass  may  be  treated  with  a  drop  of  concen- 
trated nitric  acid,  the  latter  evaporated  and  the  residue 
mixed  with  sand  and  heated  to  a  high  temperature  in  a 
glass  tube.  The  benzoin  is  indicated  by  the  odor  of 
bitter  almonds  (nitrobenzol). 

[The  method  of  Peters,  as  given  by  Leffmann,  is  as 
follows:  "  The  material  is  made  slightly  acid  and  ex- 
tracted with  chloroform,  which  is  then  evaporated  spon- 
taneously. The  vessel  containing  the  residue  is  placed 
in  melting  ice,  2  c.c.  of  sulphuric  acid  added,  and  stirred 
until  the  residue  is  dissolved.  Barium  dioxide  is  dusted 
into  the  mass,  with  constant  stirring,  until  the  liquid 
begins  to  foam,  when  3  c.c.  of  hydrogen  dioxide  (3  per 
cent.)  are  added  drop  by  drop.  The  dish  is  then  re- 
moved from  the  cold  bath,  the  contents  diluted  with 
water  to  convenient  bulk,  and  filtered.  The  acid  filtrate 
is  extracted  with  chloroform.  The  benzoic  acid  will  have 
been  converted  into  salicylic  acid  by  the  process  and  the 
latter  may  be  detected  by  dilute  solution  of  ferric 
chloride  or  ammonio-ferric  sulphate."  L.P.] 

d.  Potassium  bichromate  is  used  by  chemists  as  a 
preservative  for  milk  samples.  It  is  seldom  used  as  a 
preservative  of  market  milk.  This  poisonous  material  is 
easily  detected,  if  one  mixes  together  equal  quantities 
of  milk  and  of  a  1  per  cent,  solution  of  nitrate  of  silver. 

5 


66  MILK  HYGIENE 

If  potassium  bichromate  be  present,  the  mixture  has  a 
yellow  or  reddish-yellow  color. 

e.  Formalin  or  formol  is  a  40  per  cent,  solution  in 
water  of  formaldehyde.  It  is  a  superior  disinfectant 
and  is  being  employed  more  and  more.  The  presence  of 
0.008  per  cent,  formaldehyde  (=0.02  per  cent,  formalin) 
is  able  to  check  coagulation  of  milk  for  100  hours.  The 
addition  of  formalin  causes  no  change  in  the  fats,  there- 
fore it  may  be  used  to  advantage  in  samples  taken  for 
fat  determinations.  Formaldehyde  has,  however,  a  very 
decided  effect  on  albumin  and  as  it  has  a  deadly  effect  on 
the  protoplasma  of  bacteria,  so  it  is  also  a  powerful  poi- 
son for  the  animal  cells  and  tissues.  Investigations  by 
Annett  have  proven  that  the  addition  of  formalin  to 
milk,  even  in  the  proportion  of  1  to  50,000  may  be  injur- 
ious, especially  for  young  animals,  and  even  to  the  point 
of  causing  death.  The  addition  of  formalin  to  milk 
should  therefore  be  rigorously  prohibited. 

There  are  many  ways  of  detecting  formalin  in  milk : 

1.  100  c.c.  of  milk  are  distilled;  when  about  20  c.c. 
are  evaporated,  the  distillate  is  tested  by  the  addition 
of  5  drops  of  ammoniacal  solution  of  silver  nitrate  (1  gr. 
silver  nitrate  is  dissolved  in  30  parts  of    water    and 
enough  diluted  ammonia  water  is  added  so  that  the  sedi- 
ment which  appears  is  again  dissolved ;  then  it  is  diluted 
to  50  c.c.).     After  the  tube  has  been  shaken,  it  is  left 
standing  in  the  dark  for  some  hours.     The  presence  of 
formalin  is  shown  by  a  black  sediment  or  by  a  black  color 
of  the  liquid  (Thompson). 

2.  In  many  cases  it  is  sufficient  to  add  the  silver  solu- 
tion directly  to  the  milk,  since  this  either  colors  it  black 
at  once  or  gives  it  a  brownish  color  if  left  standing  in 
the  dark. 

3.  According  to  Lebbins,  a  test  may  be  made  by  the 
addition  of  a  little  resorcin  and  50  per  cent,  solution  of 


ADDITION  OF  ANTISEPTICS  67 

sodium  hydroxide  followed  by  boiling.  Distinct  red 
color  shows  the  presence  of  formalin. 

4.  Deniges  recommends  the  fuchsin  method:  To  40 
c.c.  of  a  0.5  per  cent,  solution  of  fuchsin  are  added  250 
c.c.  of  water,  10  c.c.  of  a  solution  of  sodium  bisulphite 
and  100  c.c.  pure  sulphuric  acid.  Upon  standing,  the 
liquid  becomes  decolorized.  To  10  c.c.  of  the  milk  under 
examination  is  added  1  c.c.  of  the  prepared  decolorized 
fuchsin  solution ;  after  5  to  6  minutes  at  the  most,  if  for- 
maldehyde be  present,  an  intense  carmine  red  appears, 
which  becomes  violet  blue  upon  the  addition  of  2  c.c. 
hydrochloric  acid. 

[5.  Richmond  has  modified  and  simplified  Hehners' 
test  so  that  it  is  most  convenient  in  milk  inspection.  It 
is  made  as  follows :  To  a  small  quantity  of  milk,  in  a 
test  tube,  add  an  equal  quantity  of  water.  Pour  a  little 
90  per  cent,  commercial  sulphuric  acid  down  the  wall  of 
the  tube  so  that  it  will  form  a  layer  at  the  bottom.  If 
formaldehyde  be  present,  a  bluish  or  violet  zone  devel- 
ops at  the  junction  of  the  acid  and  milk.  If  no  formal- 
dehyde be  present,  a  faint,  slightly  greenish  ring  forms. 
This  test  is  effective  even  when  so  little  formaldehyde  is 
present  as  1  part  in  200,000. 

6.  Leffmann  10  recommends  the  following  test,  as  one 
of  the  most  delicate  and  positive :  "  To  a  few  c.c.  of  the 
suspected  liquid,  a  pinch  of  phenylhydrazin  hydrochlo- 
ride  is  added,  the  liquid  shaken  and  a  drop  of  a  dilute 
solution  of  sodium  nitroprusside  added  and  then  a  few 
drops  of  sodium  hydroxide.  Milk  containing  formalde- 
hyde gives  a  grayish  green.  If  the  test  is  applied  to  the 
pure  solution  obtained  by  distilling  the  sample  a  char- 
acteristic deep  blue  is  produced. " 

In  distilling  milk  to  obtain  a  distillate  containing  f  or- 

10  Analysis  of  Milk  and  Milk  Products. 


68  MILK  HYGIENE 

maldehyde  for  testing  it  is  important  to  know  that, 
according  to  the  researches  of  Smith  and  Leonard,  only 
a  small  part  of  the  formaldehyde  is  distilled  over;  if 
the  milk  is  rendered  alkaline  even  less  is  collected,  but 
if  the  milk  is  acidulated  a  larger  proportion  goes  into 
the  distillate.  B.  H.  Smith  (as  reported  by  Leffmann) 
has  shown  that  if  100  c.c.  of  the  milk  sample  be  mixed 
with  1  c.c.  of  dilute  sulphuric  acid,  of  a  strength  of  one 
of  acid  to  three  of  water,  and  distilled,  one-third  of  the 
formaldehyde  present  will  come  over  in  the  first  20  c.c. 
of  the  distillate.  L.P.] 

/.  Alkalies.  In  connection  with  antiseptics,  the  ad- 
dition of  alkalies  should  be  mentioned.  To  be  sure, 
these  do  not  have  an  antiseptic  effect,  but  still,  by  the 
neutralization  of  the  acid  formed,  they  hide  changes  and 
conceal  the  fact  that  the  milk  is,  perhaps,  already 
spoiled.  In  this  connection  the  substances  to  be  consid- 
ered are  carbonate  and  bicarbonate  of  soda,  also  chalk 
and  potash.  A  distinct  alkaline  reaction  of  milk  to  lit- 
mus paper  points  to  such  an  addition  of  alkali  and 
demands  a  further  test  with  rosolic  acid. 

Ten  c.c.  of  milk  are  mixed  with  10  c.c.  alcohol  (96  per 
cent.)  and  a  few  drops  of  a  1  per  cent,  solution  of  rosolic 
acid  are  added.  Pure  milk  will  become  brownish  yel- 
low, while  milk  treated  with  alkalies  takes  on  a  rose  red 
color.  (Hilger,  C.  Schmidt.) 

III.    ABSORPTION  OF  ODORS 

Milk  possesses  a  peculiar  power  to  absorb  odors.  It 
was  mentioned  above  that  goat 's  milk  which  is  drawn  in 
the  stable  in  which  the  bucks  are  stalled  absorbs  some- 
thing of  the  same  clinging,  unpleasant,  characteristic 
odor.  Likewise,  cow's  milk  assumes  a  foreign  odor  and 
a  false  taste  when  it  stands  in  a  place  where  there  are 
strongly  smelling  substances  and  especially  when  it  is 


ABSORPTION  OF  ODORS  69 

milked,  poured  or  aerated  in  such  a  place.  The  odor  of 
tobacco  is  taken  up  by  milk.  Oil  of  turpentine,  other 
volatile  oils  and  asafoetida  may  give  an  unpleasant  odor 
and  taste  to  milk.  In  this  respect  some  of  the  worst 
substances  are  carbolic  acid,  cresol  preparations  (creo- 
lin,  lysol,  etc.)  and  chlorine,  when  these  materials  are 
used  for  disinfecting  stables  or  dairies.  The  odor  may 
last  in  these  places  for  several  days  and  the  milk  will 
take  the  abnormal  taste  just  as  long.  A  mixture  of  car- 
bolic acid  or  cresol  preparations  (crude  carbolic  acid) 
and  chloride  of  lime  has  been  used  for  the  purpose  of 
making  the  disinfectant  more  effective.  This  is  not  to 
be  recommended,  as  trichlorphenol  or  trichlorcresol  are 
formed,  compounds  that  have  a  more  penetrating  and 
lasting  "  carbolic  odor  "  than  the  separate  materials. 
Milk  which  is  drawn  in  stables  or  kept  in  places  which 
are  disinfected  in  this  way  is  useless,  sometimes  for 
weeks. 

St.  Friis  has  given  a  good  example  of  this :  a  large 
dairy  in  Copenhagen  was  in  a  state  of  tumult  because 
some  of  the  customers  complained  that  the  milk  deliv- 
ered tasted  of  carbolic  acid.  The  next  day  the  milk 
from  the  farms  was  examined  separately,  and  it  was 
found  that  all  the  milk,  about  500  quarts,  from  a  certain 
herd  of  50  cows,  smelled  and  tasted  so  strongly  of  car- 
bolic acid  that  it  was  declared  unfit  for  use  as  food.  So 
this  milk  was  churned,  as  it  was  also  the  following 
days ;  but  the  butter  had  the  same  taint  and  was  almost 
worthless.  Not  till  the  fifth  day  was  the  milk  so 
free  from  taint  that  it  could  be  used.  This  is  the 
explanation  of  the  origin  of  the  trouble:  the  stable  on 
the  farm  in  question  was  cleaned  and  disinfected  with 
a  2  per  cent,  solution  of  carbolic  acid  to  which  was 
added  a  small  quantity  of  chloride  of  lime.  The  stable 
was  aired  for  two  days  before  it  was  used  again, 


70  MILK  HYGIENE 

when  the  milk  in  which  the  defect  was  discovered  was 
drawn. 

IV.    TRANSMISSION  OF  INFECTION  BY  MILK 
FROM  CATTLE  TO  MAN 

A  series  of  specific  diseases  are  common  to  cattle  and 
man,  and  the  pyogenic  bacteria  of  man  occur  in  different 
diseases  of  cattle.  Therefore,  the  question  is  pertinent : 
Can  milk,  before  it  is  drawn,  contain  bacteria  that  are 
pathogenic  for  man!  It  is  quite  natural  that  this  may 
occur  when  the  disease  affects  the  udder ;  but  how  is  it 
with  diseases  without  this  local  manifestation!  Differ- 
ent answers  have  been  given;  some  investigators  affirm 
that  such  an  excretion  of  bacteria  regularly  takes  place 
through  the  udder;  others  (Jensen,  Gartner,  etc.)  insist 
that  this  is  not  the  case,  that  such  excretion  is  gen- 
erally limited  to  cases  in  which,  during  the  course  of  the 
disease,  local  changes  appear  in  the  udder  tissue  (hem- 
orrhage, inflammation),  and  that  anthrax  bacilli,  for 
example,  by  no  means  always  pass  from  the  blood  to  the 
milk  of  the  infected  cow.  An  exceptional  condition 
occurs  in  foot-and-mouth  disease,  as  in  this  malady  the 
milk  contains  much  infectious  matter.  But  it  will  be 
shown  later  that  the  milk  from  cows  with  this  disease 
shows  a  decided  departure  from  the  normal,  so  that  it  is 
probable  that  here,  too,  the  excretion  of  infectious  mate- 
rial is  associated  with  pathological  change  in  the  udder 
tissue. 

In  the  case  of  certain  diseases  of  cows,  it  may  occur 
that  pathogenic  micro-organisms  become  mixed  with  the 
milk  during  milking  and,  from  a  practical  standpoint, 
this  has,  in  effect,  the  same  significance  as  an  excretion 
through  the  udder. 

A  more  minute  account  of  the  diseases  of  cattle 
which  may  cause  a  direct  contamination  of  milk  with 
pathogenic  microbes  will  be  given  below. 


INFECTION  BY  MILK  71 

a.  Tuberculosis.  During  recent  years  quite  reliable 
information  has  been  obtained  concerning  the  preva- 
lence of  tuberculosis  in  cattle,  partly  from  the  abattoirs 
and  partly  from  the  use  of  the  tuberculin  test. 

The  abattoir  statistics  of  Denmark  show  differences 
in  the  prevalence  of  this  disease.  In  Copenhagen,  30  per 
cent,  of  the  mature  cattle  are  affected ;  the  same  is  true  in 
Odense,  while  Arrhus  reports  a  greater  percentage. 

In  consequence  of  the  results  obtained  from  the 
tuberculin  test,  Bang  regards  it  as  probable  that  in  Den- 
mark half  of  the  small  herds  of  from  1  to  9  members  are 
free  from  tuberculosis,  but  only  a  fourth  of  the  herds  of 
medium  size  of  from  10  to  49  animals  are  free,  and  of 
the  large  herds  only  a  few  are  exempt.  Concerning  the 
proportions  in  certain  herds,  the  most  of  the  animals 
may  be  healthy  and  tuberculosis  limited  to  a  few  individ- 
uals, but  usually  the  disease  is  more  widely  distributed 
and,  in  large  herds,  often  from  80  to  90  per  cent.,  or  even 
a  larger  number  are  affected. 

The  conditions  in  neighboring  countries  are  about 
the  same.  Tuberculosis  of  cattle,  for  example,  is 
scarcely  less  extended  in  Sweden,  North  Germany, 
Belgium  and  England  than  in  Denmark,  while  it  is  less 
frequent  in  Norway  and  South  Germany.  [This  disease 
is  also  prevalent  in  certain  parts  of  America,  especially 
in  the  leading  dairy  sections  of  the  Eastern  United 
States.] 

The  localization  of  tuberculosis  in  the  udder  is  of 
especial  interest  in  connection  with  milk  control,  since, 
when  this  condition  is  present,  milk  is  always  contam- 
inated with  tubercle  bacilli.  But  in  certain  other  forms, 
as  uterine  and  intestinal  tuberculosis,  great  quantities  of 
bacilli  are  eliminated  with  the  discharges  and  the  excre- 
tions that  soil  the  hind  quarters,  so  these  forms  may 
easily  be  the  indirect  cause  of  infection  of  the  milk.  This 


72  MILK  HYGIENE 

applies  also,  to  a  less  degree,  to  animals  that  have 
tuberculous  broncho-pneumonia. 

There  are  no  reliable  statistics  to  show  the  preva- 
lence of  udder  tuberculosis  of  the  cow  in  Denmark ;  but 
the  operation  of  the  law  requiring  the  compulsory 
slaughter  of  cows  with  tuberculosis  of  the  udder  shows 
it  to  be  of  quite  common  occurrence.  For  this  cause  407 
cows  were  killed  during  1898-99 ;  592  in  1899-1900 ;  610 
the  following  year ;  and  584  in  1901-1902.  From  Saxony 
it  is  reported  that  from  1888  to  1897,  1.1  to  3.7  per  cent, 
of  the  tuberculous  cows  killed  in  the  slaughter  houses 
were  affected  with  udder  tuberculosis,  and  in  the  whole 
German  Empire  in  1888-89,  the  percentage  of  udder 
tuberculosis  among  the  tuberculous  cows  killed  was  1.62. 
Ostertag  rates  the  prevalence  of  udder  tuberculosis  at 
4  per  cent,  of  all  tuberculous  cows.  Probably  cows 
reacting  to  the  tuberculin  test  are  not  to  be  understood 
among  these,  but  only  such  as  are  found  after  slaughter, 
by  superficial  examination,  to  be  tuberculous.  The  num- 
ber of  cows  with  udder  tuberculosis  is,  without  doubt, 
very  great,  and  in  connection  with  the  control  of  milk 
one  cannot  rate  the  significance  of  this  disease  too 
highly. 

There  is  no  information  at  hand  concerning  the  prev- 
alence of  tuberculosis  of  the  uterus.  Judging  from  the 
numerous  specimens  showing  this  lesion,  received  from 
the  city  abattoir  of  Copenhagen,  it  appears  to  be  prob- 
able that  this  manifestation  is  quite  common. 

In  regard  to  tuberculosis  of  the  intestines,  it  is 
known  that  in  mature  cattle  the  disease  follows  tuber- 
culosis of  the  lungs  and  liver,  especially  in  the  later 
stages;  and  it  is  recognized  with  difficulty  by  clinical 
examination. 

It  has  been  affirmed — within  recent  years,  by  Eabin- 
owitsch  and  Kempner — that  the  excretion  of  tubercle 


TUBEKCULOSIS  73 

bacilli  in  milk  quite  frequently  occurs  not  only  from 
cows  that  have  advanced  tuberculosis,  but  often  even 
from  animals  which  react  to  the  tuberculin  test,  but 
show  no  clinical  signs  of  disease.  Numerous  investiga- 
tions (Bang,  Nocard,0stertag  and  several  others)  do  not 
agree  with  the  results  of  Rabinowitsch  and  Kempner. 
It  appears  to  be  probable  that  an  excretion  of  tubercle 
bacilli  in  the  milk  takes  place  only  when  lesions  of  tuber- 
culosis are  present  in  the  udder  tissue ;  but  these  may  be 
so  young  and  small  that  they  are  not  apparent  upon 
clinical  examination,  and  are  also  difficult  to  see  in  dis- 
section. It  is  not  impossible,  however,  that  when  bacilli 
circulate  in  the  blood  in  great  quantity  they  may  pass 
directly  into  the  milk;  but  this  cannot  be  a  frequent 
occurrence.  As  early  stages  of  udder  tuberculosis  are 
not  revealed  by  clinical  examination,  one  must  act  upon 
the  assumption  that  not  only  cows  with  evident  udder 
or  miliary  tuberculosis  give  milk  containing  tubercle 
bacilli,  but  also  that  this  may  be  the  case  with  many  cows 
having  advanced  tuberculosis,  yet  without  changes  in 
the  udder  that  can  be  detected  by  clinical  examination. 
Even  cows  that  are  apparently  affected  with  tubercu- 
losis only  to  a  slight  degree,  or  those  that  appear  by 
clinical  examination  to  be  perfectly  sound,  may  give 
tuberculous  milk,  in  some  cases,  because  very  early 
metastases  occur  to  the  udder  and  in  others  because  this 
organ  appears  occasionally  to  be  the  seat  of  primary 
tuberculous  infection. 

It  has  been  claimed  that  cows — even  those  appearing 
clinically  sound — frequently  give  milk  containing  tuber- 
cle bacilli  after  a  tuberculin  reaction  and,  therefore,  it 
has  been  advised  to  prohibit  the  use  of  unboiled  milk 
from  such  cows,  for  a  few  months  after  the  tuberculin 
test.  This  assertion  is  wholly  untenable  and  is  com- 
pletely lacking  in  proof. 


74  MILK  HYGIENE 

On  account  of  the  great  extent  of  tuberculosis  among 
cattle  and  on  account  of  the  frequency  with  which  udder 
tuberculosis  occurs,  it  is  to  be  expected,  as  is  the  case, 
that  market  milk  very  often  contains  tubercle  bacilli 
in  appreciable  quantity.  It  is  an  established  fact  that 
mixed  milk  from  the  co-operative  creameries  contributes 
to  a  great  degree  to  the  spread  of  tuberculosis  among 
swine  and  calves.  It  has  been  proven,  too,  that  feeding 
the  dirt  removed  by  the  milk  separator  (centrifugal 
slime)  to  swine,  may  be  dangerous.  It  is  conclu- 
sively established  that  the  obligatory  pasteurization  of 
skim  milk  in  the  various  creameries,  that  has  been 
adopted  in  Denmark  in  recent  years,  has  greatly  aided 
in  checking  the  spread  of  tuberculosis  among  swine  and 
calves. 

It  is  quite  natural,  under  these  conditions,  that  it  has 
also  been  possible  to  show  that  milk  sold  in  the  cities 
contains  tubercle  bacilli  in  considerable  quantity.  St. 
Friis  made  some  investigations  of  the  milk  supply  of 
Copenhagen  in  this  connection;  in  testing  samples  of 
milk  from  twenty-eight  herds  in  Copenhagen  and  vicin- 
ity, he  found  four  tuberculous,  while  33  samples  from 
small  farms  in  Seeland  were  shown  to  be  incapable  of 
producing  tuberculosis  when  inoculated  upon  animals. 
These  results  are  better  than  those  reached  elsewhere 
through  similar  investigations.  In  the  table  on  page  75, 
essentially  after  Klimmer,  a  review  is  given  of  such 
results  from  different  cities. 

These  results  were  gained  chiefly  by  intraperitoneal 
inoculations  of  milk  upon  rabbits  and  guinea  pigs  and 
are,  therefore,  to  be  regarded,  to  a  great  degree,  as 
authentic. 

The  tubercle  bacilli  are  sufficiently  resistant  to  live 
through  the  souring  and  other  processes  necessary  in  the 
manufacture  of  milk  into  butter  and  cheese,  so  that  but- 


TUBERCULOSIS 


75 


ter,  as  well  as  cheese,  may  contain  tubercle  bacilli.  In 
some  places  this  has  been  proven  by  a  comparatively 
large  number  of  butter  tests. 

In  this  connection,  the  question  is  naturally  raised: 
Is  tuberculosis  transmissible  to  man  through  milk  and 


City. 

Number  of 
samples 
examined. 

Number  of 
samples 
in  which 
iubercle  bacilli 
were  found. 

Examination 
made  by 

28 

4 

St.  Friis 

Copenhagen           >  • 

33 

0 

St.  Friis 

Berlin      

40 

3 

Obermuller 

13 

8 

Obermuller 

Berlin                         

64 

9 

Petri 

Halle                 

9 

2 

Buege 

Genoa                       

33 

3 

Massone 

Schwiibisch-  Gmiind 

43 

5 

Ott 

Sr*li  w/'iVHsrh-Oifniiind 

28 

3 

Ott 

Milan           

54 

4 

Fiorentini 

St  Petersburg    

71 

4 

Sacharbekoff 

Dorpjit 

40 

1 

Kudinow 

Krakau                 

60 

2 

Bujwid 

Wilna                            

22 

12 

Nonewitsch 

21 

8 

v.  Hellens 

Paris                

30 

6 

Girard 

Liverpool  

144 

3 

\  Boyce,  Woodhead 

Liverpool    

24 

*      and  others 

Liverpool 

55 

3 

Delepine 

Liverpool  

125 

22 

Delepine 

Liverpool 

159 

12 

Boyce 

Liverpool  

91 

16 

Boyce 

London  .  .           

100 

7 

Klein 

dairy  products !  Avian  tuberculosis  has  been  shown  to 
differ  essentially  from  tuberculosis  of  mammals;  then 
is  tuberculosis  of  man  identical  with  that  of  cattle? 
With  the  discovery  of  the  tubercle  bacillus,  this  ques- 
tion was  answered  affirmatively,  and  this  gave  impetus 
to  the  movement  for  meat  inspection  and  dairy  inspec- 


76  MILK  HYGIENE 

tion.  Through  the  discovery  of  the  prevalence  of  feed- 
ing tuberculosis  in  swine,  horses  and  cattle,  veterina- 
rians have  emphasized  the  great  danger  that  may  come 
to  man  by  the  use  of  meat  and,  especially,  of  the  raw 
milk  of  tuberculous  animals.  Many  physicians  have 
taken  the  same  ground,  while  others  would  minimize 
this  danger  to  a  great  degree,  or  combat  its  existence 
entirely,  by  pointing  out  the  great  infrequency  of 
primary  intestinal  tuberculosis  in  man,  and  they  claim 
that  tuberculosis  of  man,  almost  without  exception, 
begins  in  the  lungs  and  is  an  infection  by  inhalation. 
There  is  still  disagreement  on  this  subject.  It  cannot  be 
denied  that  there  is  a  remarkable  difference  between 
the  prevalence  of  feeding  tuberculosis  of  calves  and  pigs 
on  the  one  side,  and  the  prevalence  of  the  unmistakable 
feeding  tuberculosis  of  man. 

Since  avian  tuberculosis  has  been  shown  to  differ 
from  tuberculosis  of  mammals,  and  since  tuberculosis 
of  dogs  is  not  transmissible  to  rabbits,  but  evokes  only 
a  temporary  local  process  (Jensen),  it  has  become  neces- 
sary to  consider  the  differences  between  tubercle  bacilli 
from  different  sources  and,  especially,  to  study  experi- 
mentally the  relation  of  cattle  tuberculosis  to  tubercu- 
losis of  man.  Of  investigations  undertaken  in  this  line, 
those  of  Th.  Smith  and  Frothingham  are  valuable 
because  they  show  a  certain  difference  in  the  bacilli  of 
cattle  from  those  of  man  and  prove  that  tubercle  bacilli 
of  man  possess  but  slight  virulence  for  cattle.  This 
question  has  become  especially  interesting  since  the 
tuberculosis  congress  in  London  in  1901,  when  Koch 
gave  the  results  of  experiments  that  he  had  conducted 
in  connection  with  Schiitz  and,  on  the  basis  of  these,  he 
believed  he  could  affirm  that  tuberculosis  of  man  is  not 
transmissible  to  cattle  and,  on  the  other  hand,  that 
tuberculosis  of  cattle  is  probably  not  transferred  to 


TUBERCULOSIS  77 

man.  In  support  of  the  latter  statement,  Koch  produced 
statistics  which  were  said  to  prove  the  great  inf requency 
of  man's  infection  with  tuberculosis  through  food. 

It  is  evident  that  the  question  of  the  identity  or  non- 
identity  of  tuberculosis  of  man  and  cattle  is  of  great 
importance  in  the  control  of  the  milk  supply.  Koch,  con- 
sequently, drew  the  conclusion  from  his  investigations 
that  the  control  of  meat  and  milk,  so  far  as  tuberculosis 
is  concerned,  is  superfluous  and  unnecessary.  There- 
fore, we  have  all  the  more  reason  for  a  closer  consid- 
eration of  the  three  questions  placed  in  the  foreground 
by  Koch's  report. 

1.  Is  tuberculosis  from  food  infection  rare  in  man? 

2.  Can  human  tuberculosis  be  transmitted  to  cattle? 

3.  Can  it  be  proven  that  tuberculosis   of  cattle  is 
transmissible  to  man? 

If  we  first  consider  the  question  of  the  frequency  of 
the  occurrence  of  tuberculosis  in  man  from  infection 
through  his  food,  it  will  be  seen  at  once  that  differences 
of  opinion  exist  concerning  the  modes  of  infection.  The 
usual  opinion  (until  quite  recently)  is  that  by  far  the 
greatest  number  of  cases  of  tuberculosis  in  man  are 
caused  by  inhaling  the  dry  bacilli;  there  is,  however, 
opposition  to  this  view.  Ribbert  and  Aufrecht  have 
concluded  that  tuberculosis  of  the  lungs  is  of  embolic 
origin  and  others  (Grawitz)  have  found  the  tonsils  to  be 
among  the  most  favorable  places  for  the  admission  of 
bacilli.  Observations  on  animals,  particularly  on  swine 
and  monkeys,  caution  us  not  to  draw  definite  conclusions 
in  relation  to  the  mode  of  infection  from  the  gross  ana- 
tomical lesions.  Thus,  for  example,  with  swine  that 
are  infected  almost  exclusively  through  the  digestive 
canal,  tuberculosis  of  the  intestines  is  an  exception, 
while  miliary  tuberculosis  of  the  lungs  often  leads  to  a 
rapidly  developing  caseous  pneumonia. 


78  MILK  HYGIENE 

Moreover,  tuberculosis  is  undoubtedly  not  so  infre- 
quently caused  by  the  food  (primary  tuberculosis  of 
the  intestines  and  mesenteric  glands)  as  Koch  affirms. 
The  available  statistics  concerning  the  prevalence  of 
abdominal  tuberculosis  differ  considerably.  While  the 
English  tables  show  the  prevalence  of  "  tabes  mesen- 
terica  "  at  about  10  per  cent,  of  all  cases  of  tuberculo- 
sis and  at  about  30  per  cent,  of  all  cases  of  tuberculosis 
in  children,  the  corresponding  figures  for  Berlin  are 

(1898)  1.8    per    cent,    and    2.8    per    cent.,    for    Paris 
(1897)  1.33  per  cent,  and  1.65  per  cent.,  for  New  York 

(1899)  0.47  per  cent. -and  2.86  per  cent,  and,  finally,  for 
Boston  (1900)  1.14  per  cent,  and  4.35  per  cent.11 

This  difference  is,  no  doubt,  largely  due  to  differ- 
ent interpretations  of  the  post-mortem  findings  [and  to 
the  different  degrees  of  prevalence  of  tuberculosis  among 
cattle]  but  a  partial  explanation  may  also  be  found  in 
the  fact  that  most  of  the  milk  in  England  is  used  in  the 
raw  state.  From  some  of  the  German  states  there  are 
reports  (Heller  and  Seitz)  concerning  the  rather  frequent 
occurrence  of  "alimentary  tuberculosis"  in  children.  As 
for  Copenhagen,  Fibiger  has  stated  that  primary  in- 
fection of  the  intestines  and  of  the  mesenteric  glands  is 
not  infrequent  with  children.  Cases  also  occur  in  adults 
that  are  most  naturally  pronounced  to  be  primary 
intestinal  tuberculosis. 

In  reference  to  the  second  question — the  possibility 
of  the  transmission  of  human  tuberculosis  to  cattle- 
investigations  have  been  going  on  for  some  time  that 
prove  that  transmission  may  be  effected  by  inoculation. 
After  Koch's  report  appeared,  a  great  number  of  experi- 
ments were  undertaken  to  throw  light  upon  this  ques- 
tion, the  results  of  which  are  partially  published.  Fib- 

11  Salmon :  Relation  of  bovine  tuberculosis  to  the  public  health. 
1901. 


OF  THE     "      ^V 

VERSITY   1 

OF  / 

\^X    79 


iger  has  given  a  review  of  these  :  in  61  series  of  experi- 
ments, 81  calves,  heifers,  cows  and  oxen  were  inoculated 
with  human  tuberculosis  ;  in  41  experiments  on  51  ani- 
mals the  result  of  the  inoculation  was  positive.  In 
many  cases  the  inoculation  caused  only  local  processes 
extending  to  near-by  glands,  but  the  experimental  ani- 
mals were  all  killed  comparatively  early,  so  that  the  dis- 
ease could  well  have  spread  further  if  the  animals  had 
lived  longer.  As  is  known,  tuberculosis  of  cattle  fre- 
quently remains  local  for  a  long  time.  Sometimes  the 
inoculations  caused  violent  tuberculosis  in  the  experi- 
mental calves,  and  this  was  particularly  the  case  when 
the  inoculation  material  came  from  patients  affected 
with  "  feeding  tuberculosis.  "  (Bavenel,  Wolff,  Fibiger 
and  Jensen,  Westenhoeffer.) 

The  clinical  observations  that  may  be  cited  in  answer 
to  the  third  question  seem  to  prove  that  bovine  tubercu- 
losis is  transmissible  to  man.  There  are  many  observa- 
tions, principally  upon  veterinarians  and  butchers,  of 
tuberculous  inoculation  communicated  to  the  hands  and 
fingers  through  cuts  while  working  with  tuberculous 
organs  of  cattle.  In  some  cases  these  were  only  local 
lesions  that  were  healed  by  surgical  means;  in  others, 
the  disease  extended  to  the  sheaths  of  the  tendons  and 
glands,  and  in  still  others,  in  the  course  of  time,  it 
appeared  to  develop  into  lung  tuberculosis.  Greater 
interest  attaches  to  cases  of  feeding  tuberculosis  which 
may  with  great  probability  be  traced  to  infection 
through  milk  of  tuberculous  animals.  A  large  number  of 
such  cases  have  been  given,  from  which  the  following 
have  been  chosen  : 

1.  The  17-year-old  daughter  of  Prof.  Gosse  died  of  abdominal 
tuberculosis    after    drinking   milk    from    cows    affected    with    udder 
tuberculosis.     Other  sources  of  infection  could  not  be  discovered. 

2.  Olivier's   observation   concerns  one  of  the  best  proven  cases 


80  MILK  HYGIENE 

of  transmission  by  milk:  In  a  boarding  school  12  young  girls 
became  ill  with  signs  of  intestinal  tuberculosis,  and  5  of  them 
died.  All  came  from  healthy  families  and  no  source  of  infection 
was  found  but  one  cow  which  supplied  milk  for  the  school  and  was 
shown  to  be  affected  with  tuberculosis  of  the  udder. 

3.  Demme  has  reported  the  following:  In  the  children's  hospital 
Bern,  four  children  died  of  intestinal  and  mesenteric  glandular  tuber- 
culosis.    He  was  able  to  exclude  all  other  sources  of  infection  and  to 
prove  that  the  milk  came  from  tuberculous  cows. 

4.  Hills  tells  of  a  21  months  old  child  that  was   affected  with 
intestinal  tuberculosis  three  months  after  making  an  eight-day  visit 
to  an  uncle  where  it  had  drunk  the  milk  of  a  cow  having  advanced 
tuberculosis.      The    child    died    of    tuberculosis.      Other    sources    of 
infection  were  excluded  and  another  child   fed  only  with  sterilized 
milk  remained  healthy. 

5.  Ernst   reports   that   three   children   of   the   same   family   died 
of  tuberculosis  after  drinking  milk  from  a  cow  that   later  died  of 
general  tuberculosis  with  udder  involvement. 

Leonliardt,  Sonntag,  Hermsdorff,  Klebs,  Rotch, 
Lydtin  and  Stang,  Johne  and  many  others  have  reported 
quite  similar  observations. 

Of  particular  interest  are  the  cases  reported  by 
Ravenel,  Fibiger  and  Jensen,  and  many  others,  of  tuber- 
culosis of  children  with  prominent  lesions  in  the  diges- 
tive canal,  while  the  tubercle  bacilli  present  were  so 
virulent  for  cattle  that  the  origin  of  the  cases  in  ques- 
tion were  referred,  with  the  greatest  probability,  to 
infection  through  the  milk. 

If  one  considers  that  feeding  tuberculosis  is  by  no 
means  infrequent  in  man,  and  occurs  quite  frequently  in 
children,  that  human  tuberculosis  is  often  transmissible 
to  cattle,  and  that  clinical  knowledge  argues  for  trans- 
mission of  bovine  tuberculosis  to  man,  and  if  one  con- 
siders that  tubercle  bacilli  from  cattle  have  been  proven 
at  least  as  dangerous  and  generally  more  virulent  for 
all  animals  than  tubercle  bacilli  from  man,  then  milk 
containing  tubercle  bacilli  must  be  regarded  as  most 


TUBERCULOSIS  81 

dangerous  to  health.  Therefore,  it  must  be  one  of  the 
most  important  purposes  in  milk  control  to  prevent  the 
sale  of  such  milk. 

It  is  a  difficult  task  to  detect  tubercle  bacilli  in  milk. 
Intraperitoneal  injections  of  the  milk  into  guinea  pigs 
and  rabbits  may  be  made,  but  sometimes  many  of  the 
animals  die  from  other  infections  (cocci ;  other  bacteria). 
Sometimes  so  long  a  time  elapses  before  the  results  are 
available  that  the  experiment  has  lost  much  of  its  prac- 
tical value.  Moreover,  certain  similar  bacteria  (acid- 
fast  bacteria)  may  cause  alterations  in  the  experimental 
animals  which  can  hardly  be  distinguished  from  tuber- 
culosis. The  detection  of  tubercle  bacilli  in  milk  by 
microscopic  examination  is  difficult;  a  direct  examina- 
tion will  very  seldom  give  results ;  so  one  must  depend 
either  on  centrifuging,  whereby  all  the  little  flakes  to 
which  the  bacilli  usually  adhere  may  be  thrown  down, 
and  then  examined,  or  other  means  for  separation  must 
be  used  (see  below)  so  that  the  bacilli  may  be  precipi- 
tated without  too  great  a  quantity  of  sediment. 

Since  the  number  of  tubercle  bacilli  in  mixed  milk  is, 
at  most,  but  small,  only  a  positive  result  of  the  examina- 
tion can  be  final,  and  even  then  the  result  is  doubtful 
since,  as  mentioned  before,  "  pseudotubercle  bacilli  ' 
may  appear  in  milk  (see  below)  which  are  like  the  tuber- 
cle bacilli  in  respect  to  staining  and  are  similar  also  in 
morphology. 

We  must,  therefore,  depend  on  the  clinical  examina- 
tion of  the  cows  in  the  herd  itself,  if  we  would  check  the 
passage  of  tubercle  bacilli  into  milk.  This  inspection 
must  be  directed  especially  to  tuberculosis  of  the  udder, 
uterus  and  intestines  and,  at  the  same  time,  to  miliary 
tuberculosis  and  to  all  cases  of  lung  tuberculosis  suf- 
ficiently developed  to  cause  the  appearance  of  clinical 
signs.  But  the  inspection  must  not  be  clinical  alone ;  in 


82  MILK  HYGIENE 

respect  to  the  first  forms  of  tuberculosis  mentioned,  it 
must  be  microscopic  as  well,  for  tubercle  bacilli  may  be 
found  in  the  milk,  in  the  uterine  secretion  and  some- 
times in  the  excrement  when  the  clinical  symptoms  are 
such  as  merely  to  arouse  suspicion.  Such  an  examina- 
tion of  the  herd,  to  be  efficient,  should  occur  frequently, 
at  least  every  fortnight,  since  this  disease,  and  especially 
tuberculosis  of  the  udder,  may  develop  materially  in  this 
time.12 

It  can  hardly  be  stated,  in  general,  how  strict  the 
regulations  regarding  tuberculous  animals  should  be. 
In  some  countries  it  is  only  forbidden  by  law  to  use  milk 
unboiled  from  cows  with  udder  tuberculosis.  Milk  from 
cows  with  tuberculosis  of  the  uterus,  of  the  intestines 
and  miliary  tuberculosis,  and  also  from  cows  that  are 
cachectic,  should  not  be  permitted  to  be  sold.  It  would  be 
best,  if  it  could  be  arranged,  to  allow  the  sale  of  milk 
from  herds  in  which  there  are  tuberculous  animals  only 
under  declaration  of  the  condition  of  the  herd;  but  on 
account  of  the  great  extent  of  tuberculosis  no  such 
requirement  has  been  made.  It  is  a  reasonable  and,  at 
the  same  time,  an  absolutely  necessary  requirement  that 
the  so-called  "  nursery  milk,"  milk  intended  especially 
for  small  children  and  invalids,  should  come  from  a 
herd  which  is  entirely  free  from  tuberculosis,  that  is,  a 
herd  composed  of  cows  none  of  which  have  reacted  to 
the  tuberculin  test. 

Tests. — The  discovery  of  tubercle  bacilli  in  the  milk 
of  individual  cows  with  advanced  udder  tuberculosis  and 
in  the  discharge  from  the  uterus,  is  usually  easy.  A 
small  quantity  of  the  fluid  or  a  little  flake  or  lump  is 
spread  upon  a  cover  glass,  it  is  fixed  in  the  usual  way  in 
the  flame  and  then  stained  according  to  one  of  the 
methods  given  below. 

12  This  relates  to  herds  known  to  be  infected.     [L.  P.] 


TUBERCULOSIS  83 

1.  Ziehl-Neelsen  method.    One  grm.  of  fuchsin  is  dis- 
solved in  10  c.c.  alcohol  and  100  c.c.  5  per  cent,  phenol 
water   and   the   solution   is   filtered.      By  means   of  a 
pipette,    a   liberal    quantity    of   this    staining   fluid   is 
dropped  on  the  cover  glass  which  is  held  by  pincers 
above    a    flame    a    couple    of   minutes    until    the    fluid 
boils  briskly,  but  without  drying.    Then  the  cover  glass 
is  rinsed  with  water  and  treated  for  a  few  seconds 
with  25  per  cent,  sulphuric  acid  and  again  rinsed  with 
water.     If  the  red  color  is  still  distinct,  the  treatment 
with  acid  is   repeated  and  the  cover  glass   is  rinsed 
carefully  with  a  little  alcohol.    Finally,  a  few  drops  of 
watery  solution  of  methylene  blue  are  dropped  upon  it, 
after  which  it  is  again  rinsed  with  water  and  mounted. 

2.  Kitt's  method.    To  100  c.c.  saturated  anilin  water 
are  added  1  c.c.  of  a  1  per  cent,  sodium  hydrate  solution 
and  4  to  5  grm.  of  fuchsin.     Or,  the  above  mentioned 
phenol-fuchsin  solution  may  be  used.    The  cover  glass  is 
treated  as  described  above,  then  rinsed  and  dipped  for 
one-half  minute  in  a  fluid  consisting  of  50  c.c.  alcohol,  30 
c.c.  water  and  20  c.c.  nitric  acid,  to  which  has  been 
added  as  much  methylene  blue  as  the  fluid  will  dissolve. 
Finally,  the  slide  is  rinsed  with  water. 

3.  Czapleiv ski's  method.     The  staining  is  done  by 
heating  with  phenol-fuchsin  solution  as  given  above. 
Allow  the  staining  fluid  to  run  off  and,  without  rinsing, 
dip  the  cover  glass  six  to  ten  times  into  a  concentrated 
alcoholic  solution  of  fluorescein  (1  grm.  in  100  c.c.  alco- 
hol).     The    double    staining    comes    from    repeatedly 
dipping  the  cover  slips  in  concentrated  alcoholic  solution 
of  methylene  blue  (5  to  100) ;  then  they  are  rinsed  in 
water.    By  this  method,  a  decoloration  of  tubercle  bacilli 
is  avoided  with  certainty. 

In  all  cases,  the  preparation  is  mounted  and  ex- 


84  MILK  HYGIENE 

amined  in  the  usual  way  with  an  immersion  lens  and 
Abbe  condenser.  The  tubercle  bacilli  are  colored  red, 
other  bacteria  and  the  rest  of  the  preparation  are 
colored  blue. 

So-called  "  acid-fast  "'  bacilli  may  occur  in  milk 
and  butter  as  well  as  in  the  excrement  of  the  cow.  These 
bacilli,  which  by  the  above  methods  are  also  colored  red, 
are  difficult  to  distinguish  with  certainty  from  the  real 
tubercle  bacilli,  even  by  microscopic  examination,  al- 
though they  are  usually  thicker  and  shorter.  Unfortu- 
nately, we  know  but  little  of  the  conditions  governing 
their  occurrence  in  milk.  There  is  reason  to  believe  that 
they  usually  occur  as  a  result  of  accidental  contamina- 
tion after  the  milk  is  drawn.  In  order  that  one  may 
be  quite  safe  in  his  conclusions  from  this  examina- 
tion, and  be  able  to  avoid  confusing  the  acid-fast  and 
tubercle  bacilli,  the  udder  secretion  or  the  discharge 
from  the  uterus  that  is  to  be  examined  microscopically 
must  be  taken  as  pure  as  possible  in  a  clean  tube  and,  if 
the  examination  cannot  be  made  at  once,  an  antiseptic  (a 
little  ether  or  chloroform,  a  few  drops  of  formalin) 
should  be  added.  Acid-fast  bacilli  accidentally  added, 
will  not  increase  under  these  conditions,  and  their  num- 
ber will  always  be  so  small  that  they  can  hardly  be  de- 
tected. It  is,  however,  not  wholly  disproven  that  such 
bacilli  may  appear  in  the  milk  before  it  is  drawn.  De 
Jong  has  reported  a  case  of  mastitis  caused  by  acid-fast 
bacilli,  but  this  is  the  only  case  of  the  sort  reported  up 
to  this  time.  From  knowledge  gained  during  the  last 
four  or  five  years  in  the  experimental  laboratory  of 
Copenhagen  from  investigations  of  milk  samples  and 
the  control  of  the  diagnosis  of  udder  tuberculosis  from 
small  samples  of  tissue  from  condemned  and  slaughtered 
cows,  it  follows  that  errors  very  seldom  occur  as  a  result 
of  confusing  these  organisms. 


PSEUDO-TUBERCLE  BACILLI  85 

When  it  comes  to  the  examination  of  milk  of  normal 
appearance,  the  question  is  usually  more  difficult,  be- 
cause the  number  of  tubercle  bacilli  is  less.  A  direct 
microscopic  examination  of  the  milk  is  rarely  useful ;  it 
is  better  to  pour  a  little  of  it  on  a  dark  surface  and  pick 
out  with  a  needle  the  small  flakes  which  are  usually 
present  and  form  the  little  lumps  of  fibrous  exudate  to 
which  the  bacilli  adhere.  Still  better  results  are  reached 
by  centrifuging  the  milk  and  examining  the  sediment. 
Any  milk  centrifuge  may  be  used  for  this  purpose  (in- 
cluding those  used  for  determining  the  amount  of  fat) 
and  it  may  be  driven  by  steam  or  by  hand  power.  Of 
course,  a  large  centrifuge  of  high  speed  is  best. 

Instead  of  the  centrifuge,  the  separation  of  tubercle 
bacilli  by  other  means  has  been  suggested. 

For  this  purpose  Biedert  employs  the  following 
method :  100  c.c.  milk  are  mixed  with  4  to  8  drops  of  solu- 
tion of  sodium  hydroxide;  the  mixture  is  well  shaken 
until  the  small  flakes  and  lumps  are  dissolved,  then  it  is 
boiled.  The  cloudy  fluid  is  poured  into  a  conical  glass 
and  left  standing  for  some  time.  The  sediment  that 
collects  in  the  point  of  the  glass  may  be  drawn  off  by  a 
pipette  and  examined  microscopically. 

The  practice  has  also  been  followed  of  submitting  the 
milk  to  special  treatment  with  chemicals  before  it  is 
centrifuged. 

Thus,  Ott  mixed  together  25  c.c.  milk,  2  c.c.  concen- 
trated ammonia  water  and  100  c.c.  of  a  mixture  of  equal 
parts  of  ether  and  petroleum  ether,  in  a  separator  flask 
with  a  glass  stopper.  After  being  shaken  and  allowed 
to  stand,  the  ammonia-casein  solution,  in  which  the 
bacilli  are  found,  is  drawn  off  from  the  bottom  and 
centrifuged. 

Hammond's  method  is  as  follows  :  100  c.c.  of  milk  are 
mixed  with  5  c.c.  of  phenol ;  15  to  30  c.c.  of  the  mixture 


86  MILK  HYGIENE 

are  placed  into  two  tubes  and  centrifuged  for  15  min- 
utes. The  fluid  is  poured  off  and  3  c.c.  of  a  5  per  cent, 
solution  of  potassium  hydroxide  are  added  to  the  sedi- 
ment. After  violent  shaking,  the  liquid  is  allowed  to 
stand  2  to  3  minutes,  then  15  c.c.  of  water  are  added  to 
it ;  it  is  shaken  and  centrifuged  20  minutes.  Then,  15  c.c. 
of  the  liquid  are  drawn  off  from  above,  while  the  residue 
is  examined  microscopically  in  the  usual  way. 

The  detection  of  tubercle  bacilli  in  milk  by  cultiva- 
tion is  most  difficult  and  without  practical  utility.  In 
doubtful  cases,  where  the  result  of  the  microscopic  exam- 
ination is  uncertain,  it  is  advantageous  to  "  harpoon  " 
the  udder,  thereby  removing  a  small  sample  of  the  deep 
tissue  of  the  udder  for  examination  microscopically  or 
by  the  inoculation  of  experimental  animals,  as  guinea 
pigs. 

Statements  of  the  temperature  at  which  tubercle 
bacilli  are  killed,  vary  greatly.  While,  in  the  first  in- 
stance, Bang  and  other  investigators  found  that  momen- 
tary heating  to  85°  C.  killed,  Legay  and  Bech  reported 
that  brief  boiling  was  not  always  sufficient,  and  Volsch 
found  that  even  repeated  boiling  would  not  always  kill 
tubercle  bacilli.  On  the  other  hand,  Th.  Smith  reached 
the  conclusion  that  even  a  far  lower  temperature  than 
those  originally  given  would  kill  with  certainty  if  the 
formation  of  a  pellicle  during  heating  was  prevented. 
According  to  the  most  recent  investigations,  carried  out 
with  the  greatest  accuracy  by  Bang  and  Stribolt,  it  is  to 
be  considered  as  proven  that  heating  at  65°  C.  for  5 
minutes  or  momentary  heating  at  70°  C.  kills  the  bacilli 
with  certainty  and  that  the  former  uncertainty  on  this 
subject  arose  principally  from  faulty  methods  in  the 
experiments.  The  observations  by  Legay,  Bech  and  sev- 
eral others  show,  however,  that  in  practice  a  very 
high  degree  of  heat  must  be  attained  to  be  safe,  and  that 


FOOT-AND-MOUTH  DISEASE  87 

even  boiling  for  a  short  time  without  especial  precau- 
tionary measures,  is  not  always  sure  to  kill  all  bacilli, 
because  there  is  a  part  of  the  milk  (little  drops  on  the 
upper  part  on  the  vessel,  bubbles,  scum  or  froth  on  the 
surface)  which  is  not  thoroughly  heated.  It  is,  there- 
fore, a  matter  of  great  importance  to  determine  whether 
the  forms  of  apparatus  used  for  pasteurization  are 
really  so  constructed  that  all  of  the  milk  is  equally  heated 
to  a  desired  temperature.  At  present,  nothing  definite 
can  be  said  about  this,  since  no  investigations  have  been 
made  to  determine  the  amount  of  froth  formation  and 
the  temperature  the  froth  reaches  in  the  different  forms 
of  apparatus.  When  market  milk  is  pasteurized  the 
functional  capacity  of  the  apparatus  should  be  very 
carefully  tested. 

5.  Foot-and-mouth  disease.  It  has  long  been  known 
that  milk  from  cows  with  f oot-and-niouth  disease  is  infec- 
tious, and  may  carry  the  disease  to  man.  A  hundred 
years  ago,  in  South  Germany,  the  use  of  milk  from  such 
cows  was  prohibited  for  use  as  food  for  man.  In  the 
lighter  forms  of  the  disease  the  milk  remains  unchanged, 
but  with  cows  badly  affected,  there  is  not  only  a  decided 
diminution  in  quantity,  but  its  appearance  and  composi- 
tion are  changed.  In  such  cases,  the  milk  becomes  thin, 
separates  a  slimy  layer  of  cream,  of  dirty  color,  and  there 
is  quite  abundant  sediment  or,  as  happens  infrequently, 
it  becomes  richer  in  fat  with  a  simultaneous  falling  off 
in  quantity.  Under  the  microscope,  leucocytes  and 
broken-down  tissue-cells  are  found  in  greater  quan- 
tity than  usual,  sometimes  red  corpuscles  also.  The 
milk  contains  a  greater  quantity  of  albumin  and  globulin 
than  usual,  so  that  when  boiled,  large  clumps  and  flakes 
separate  and  the  sugar  and  casein  fall  off  in  quantity- 
all  changes  which  are  symptomatic  of  an  admixture  of 
inflammatory  exudate. 


88  MILK  HYGIENE 

Just  how  often  the  milk  of  the  affected  cows  is  viru- 
lent, is  not  known.  Apparently,  this  is  frequently  the 
case,  and  certainly  it  is  when  the  milk  shows  the  changes 
mentioned.  The  virus  may,  moreover,  enter  the  milk  as 
it  is  being  drawn,  if  vesicles  occur  on  the  teats  or  udder. 
The  quantity  of  milk  decreases  noticeably  during  the 
course  of  the  disease  and  it  seldom  reaches  its  original 
flow  after  recovery. 

This  disease  is  very  easily  communicated  by  the  milk 
to  other  cattle,  to  swine  and,  as  is  known,  to  man.  Chil- 
dren are  especially  susceptible.  Brussenius  and  Siegel 
have  collected  a  large  number  of  the  cases  mentioned  in 
the  literature  of  foot-and-mouth  disease  in  man.  Dur- 
ing the  years  from  1878  to  1886,  16  different  epidemics 
of  the  disease  in  man  were  observed.  Not  only  were  all 
the  members  of  single  families  attacked,  but  also  numer- 
ous inhabitants  of  whole  villages  and  towns.  During 
one  epidemic,  36  died;  during  another,  23  and  during  a 
third,  16.  All  the  epidemics  occurred  simultaneously 
with  foot-and-mouth  disease  of  cattle  in  the  affected 
districts  and,  almost  without  exception,  the  infection 
came  from  the  use  of  raw  milk.  From  1886  to  1896,  172 
cases  in  man  were  reported  in  the  annual  reports  of  the 
German  Imperial  Health  Office,  66  of  which  were  traced 
to  infection  through  milk,  while  one  case  occurred  from 
the  use  of  butter  made  from  the  milk  of  an  infected  cow. 

The  course  of  the  disease  in  man  may  be  light  or 
severe  and,  as  said,  the  disease  may  end  in  death.  The 
symptoms  are :  fever  and  weakness,  conjunctivitis,  for- 
mation of  vesicles  on  the  mucous  membrane  of  the 
mouth,  the  lips,  the  ears,  the  nose,  fingers  or,  less  fre- 
quently, on  other  places  on  the  body;  besides,  nausea, 
vomiting,  diarrhrea;  sometimes  redness  of  the  skin  and 
arthralgia.  It  is  transmissible  from  man  to  man. 

The  virus  of  foot-and-mouth  disease  may  occur  even 


COWPOX  89 

in  butter,  buttermilk  and  cheese,  since  it  is  not  killed 
by  the  treatment  which  milk  undergoes  in  their 
manufacture. 

This  virus,  the  appearance  of  which  is  wholly  un- 
known (probably  on  account  of  its  ultramicroscopic 
size),  is  not  particularly  resistant.  It  has  been  proven 
by  experiments  made  during  recent  years  in  Germany 
that  the  virus  dies  after  10  minutes'  exposure  at  70°  C. 
and  by  being  heated  to  100°  C.  for  an  instant.  Experi- 
ments made  in  Denmark  seem  to  have  shown  that  pas- 
teurization at  80°  to  85°  C.,  as  is  done  in  our  cooperative 
creameries,  is,  without  doubt,  enough  to  destroy  the 
virus. 

c.  Cowpox.  This  disease  attacks  particularly  the 
teats  of  the  cow,  and  therefore  it  cannot  be  doubted  that 
during  milking  the  virus  held  in  the  vesicles  sometimes 
falls  into  the  milk.  Since  the  vaccine  virus  is  known  to 
be  very  potent,  and  since  man  is  peculiarly  susceptible 
to  it,  it  is  evident  that  the  disease  is  transmissible 
through  milk  to  man.  But,  while  there  are  numerous 
examples  of  direct  infection  on  the  hands  and  face  of 
the  milker,  there  are  only  a  few  observations  of  an 
infection  through  the  use  of  such  milk.  The  inf requency 
of  such  cases  may  come  partly  from  two  conditions, 
namely,  that  most  persons  are  early  immunized  by  com- 
pulsory vaccination  and  that  small  children  usually  drink 
the  milk  after  it  has  been  boiled  or,  at  least,  heated. 

Among  the  examples  of  this  disease  in  children,  which 
have  occurred  through  the  use  of  milk  from  infected 
cows  and  which  are  to  be  taken  as  unmistakable  trans- 
mission of  the  disease,  the  following  observation  by 
Stern  may  be  given:  Cowpox  broke  out  in  a  herd  of 
milch  cows;  a  large  number  of  children  that  had  used 
milk  from  this  herd  became  affected  with  an  eruption  on 
the  face,  which  healed,  leaving  scars. 


90  MILK  HYGIENE 

During  the  course  of  cowpox,  milk  may  undergo  quite 
noticeable  changes  in  that  it  becomes  thin  and  bluish  and 
coagulates  very  easily.  This  change  has  not  yet  been 
closely  studied,  and  it  does  not  appear  to  be  constant. 

d.  Anthrax.  During  the  course  of  anthrax,  the  secre- 
tion of  milk  falls  off  suddenly  and  decidedly.  The  milk 
secreted  is  thin  and  its  composition  is  supposed  to  be 
abnormal.  According  to  a  report  of  Monatzkows,  the 
percentage  of  sugar  and  fat  is  increased  and  the  albu- 
min decreased.  Perdix  states  that  the  milk  contains 
ammonia. 

Chamberland  and  Roux,  Nocard  and  several  other 
investigators  have  observed  that  the  milk  of  cows  af- 
fected with  anthrax  contains  virulent  bacilli.  According 
to  the  experiments  of  Monatzkows  and  of  Jensen,  this  is 
not  always  the  case.  Since  the  milk  is  often  mixed  with 
blood,  following  slight  hemorrhages  in  the  udder  tissue, 
it  is  probable  that  the  admixture  of  bacilli  occurs  only 
when  such  hemorrhages  take  place. 

As  anthrax  bacilli  are  able  to  penetrate  the  mucous 
membrane  of  the  digestive  canal  in  man,  the  milk  of  a 
cow  suffering  with  anthrax  is  to  be  considered  very  dan- 
gerous. This  was  mentioned  long  ago  by  Heusinger, 
but  so  far  as  is  known  to  the  author  there  is  only  a 
single  questionable  observation  of  such  transmission 
(Karlinski). 

The  milk  from  healthy  cows  in  a  herd  in  which  a 
case  of  anthrax  has  occurred  must  be  regarded  as  harm- 
less, for  the  disease  is  accompanied  by  striking  symp- 
toms and  bacilli  are  not  to  be  found  in  the  milk  before 
the  late  stages  of  the  disease.  Cows  that  still  appear 
healthy,  give  milk  free  from  bacilli  even  though  they  be 
affected.  Apropos  of  this,  the  following  statement  is 
contained  in  Section  26  of  the  instructions  to  the  Danish 
veterinary  police:  "  Milk  from  sick  [anthrax]  animals 


EABIES  91 

must  not  be  used  for  food  for  man  or  beast.  The  owner 
may  dispose  of  milk  from  the  healthy  members  of  the 
herd — in  so  far  as  the  sanitary  police  give  no  other 
order — unhindered,  under  the  condition  that  he  pledges 
himself  to  observe  closely  the  condition  of  the  health  of 
the  herd  and  to  separate  at  once  those  animals  which 
show  suspicious  symptoms,  such  as  lack  of  appetite, 
cessation  of  rumination,  diminution  of  milk  yield  and 
the  like.  Milk  from  animals  that  are  separated  must 
not  be  mixed  with  that  of  the  healthy  animals.'7 

The  health  authorities  may,  however,  have  good  rea- 
son to  forbid  the  sale  of  unboiled  milk  in  cases  when  the 
disease  breaks  out  violently  in  a  herd,  as  then  the  danger 
exists  that  bacilli  may  enter  the  milk  when  it  is  drawn, 
for  the  sick  animals  excrete  bacilli  with  the  bloody  ex- 
crement and  the  stable,  in  spite  of  all  care  and  disinfec- 
tion, may  be  so  thoroughly  infected  that  there  is  the 
possibility  of  contaminating  the  milk. 

e.  Rabies.  The  virus  of  rabies,  yet  unknown,  is  espe- 
cially associated  with  the  central  nervous  system  and  the 
salivary  glands.  Frequently  it  may  be  found  in  other 
glands  and  even  in  the  udder.  A  number  of  observa- 
tions by  Nocard,  Perroncito,  Bardach  and  several  others, 
have  proven  that  the  virus  may  be  secreted  with  the  milk. 
All  attempts  to  convey  the  disease  to  healthy  animals, 
through  food  containing  infectious  material,  have  thus 
far  resulted  negatively,  and  hence  numerous  opinions 
have  been  expressed  to  the  effect  that  there  is  apparently 
no  danger  to  man  in  the  use  of  milk  from  cows  that  have 
been  bitten  by  a  mad  dog  and  that  are  themselves  rabid. 

Yet,  since  the  possibility  is  always  present  that  infec- 
tion may  occur  through  a  slight  lesion  of  the  mouth  or 
pharynx,  milk  from  cows  infected  with  rabies  (cows 
that  have  been  bitten  by  rabid  dogs)  is  to  be  regarded 
as  most  dangerous  to  health. 


92  MILK  HYGIENE 

/.  Lung  plague.  According  to  the  few  investigations 
that  have  been  made,  milk  undergoes  a  considerable 
change  during  the  course  of  this  disease.  The  fat  con- 
tent is  lessened  and  the  albumin  increases  in  quantity. 
After  standing,  the  milk  is  quickly  separated  into  a 
layer  of  cream  and  a  lower  serum-like  layer.  Haukold 
affirms  that  the  milk  has  a  peculiar  odor  and  taste,  and 
may  cause  vomiting  in  man.  Wiedermann,  Lecuyer 
and  Randou  have  observed  some  cases  where,  according 
to  their  opinion,  lung  plague  has  been  carried  to  chil- 
dren through  the  use  of  milk  from  infected  cows. 
Though  at  least  one  case,  in  respect  to  its  pathological 
anatomy,  showed  great  similarity  to  the  peculiar  pneu- 
monia that  occurs  in  this  disease  of  cattle,  it  should  not 
be  regarded  as  established  that  man  is  susceptible  to 
this  disease,  and  especially  is  transmission  through  milk 
unlikely,  because  it  is  not  possible  to  prove  the  presence 
of  the  specific  virus  in  the  blood  or  in  the  milk  by 
inoculation. 

The  changed  condition  of  the  milk  is  enough,  how- 
ever, to  prohibit  its  use.  But  such  an  interdiction  is 
unnecessary  in  almost  all  civilized  countries  on  account 
of  the  regulations  of  the  veterinary  police  regarding 
this  disease. 

g.  Actinomycosis.  Actinomycosis  belongs  to  the 
comparatively  frequent  diseases  of  the  udder  of  the  cow 
where  it  apparently  originates  primarily.  Sometimes 
it  appears  as  miliary  actinomycosis  with  a  number  of 
quite  small  lesions  distributed  throughout  the  gland  af- 
fected, and  in  this  form  it  may  resemble  a  fresh  udder 
tuberculosis.  More  often,  actinomycosis  appears  as  sin- 
gle or  multiple  nodules  from  the  size  of  a  nut  to  that  of 
an  egg — these  are  surrounded  by  newly  formed  connec- 
tive tissue  and  may  break  through  the  skin  of  the  udder. 

There  are  no  recorded  investigations  concerning  the 


MASTITIS  93 

changes  in  milk  secretion  during  this  disease,  nor  have 
the  actinomyses  or  ray  fungi  yet  been  found  in  milk, 
in  which  they  probably  occur.  Man  may  be  infected 
through  the  digestive  canal  (the  mouth  and  intestines), 
just  as  cattle  are,  and  on  this  account  the  possibility  of 
contagion  through  milk  should  not  be  disregarded. 
Therefore,  milk  from  cows  affected  with  udder  actino- 
mycosis  (which,  however,  is  not  often  diagnosed  in  liv- 
ing cows)  should  not  be  used  as  food  for  man. 

h.  Inflammation  of  the  udder  (mastitis).  The  forms 
of  inflammation  of  the  udder  occurring  in  the  cow  may 
be  divided  into  the  following  principal  classes,  which 
differ  chiefly  according  to  the  grade  of  inflammation, 
the  extent  to  which  the  milk  secretion  is  checked  and  the 
character  of  the  exudate : 

1.  Mucous  catarrh; 

2.  Purulent  catarrh; 

3.  Parenchymatous,    purulent    mastitis,    ultimately 
accompanied  by  abscesses ; 

4.  Gangrenous  mastitis. 

These  forms  cannot  always  be  distinctly  separated. 
The  changes  caused  through  inflammation  of  the  udder, 
in  the  chemical  composition  of  milk    were    described 
above. 

The  various  forms  of  mastitis  are  of  microbic  origin. 
There  are  many  kinds  of  bacteria  which,  if  admitted 
to  the  milk  cistern,  may  cause  inflammation  of  the  glands 
and,  upon  examination  of  the  spontaneous  cases,  quite  a 
large  number  of  mastitis  bacteria  have  been  found, 
chiefly  such  as  cause  inflammation  elsewhere  in  the 
organism.  By  far  the  most  cases  of  udder  inflammation 
arise  from  bacteria  which  belong  to  one  of  the  following 
groups : 

1.  Streptococci,  which  usually  cause  chronic  mucous 
(slimy)  or  purulent  catarrh,  ending  with  atrophy  of  the 


94  MILK  HYGIENE 

udder  tissue  and  agalactia.     More  rarely,  streptococci 
occur  as  causative  factors  of  a  mild  catarrh  of  the  udder. 

2.  Stapliylococci,  which  sometimes  cause   a  milder 
form  of  udder  catarrh,  and  sometimes  cause  a  light 
or    moderately    severe    parenchymatous    inflammation, 
which  may  end  in  recovery,  in  abscess  formation  or  in 
contraction  of  the  udder.    The  Staphylococcus  pyogenes 
aureus  and  albus  are  found,  but  others  occur  as  well. 
In    this    group,    as    is    known,    the    differentiation    is 
difficult. 

3.  The  colon  group.    The  parenchymatous  forms  of 
mastitis  caused  by  organisms  of  this  group  may  be  mild, 
medium  or  severe,  and  they  may  end  in  spontaneous 
recovery,  necrosis,  gangrene  and  formation  of  abscesses, 
or  in   induration.     The   systemic  manifestations   may 
be  very  marked,   and   the   infection  may   even   result 
fatally. 

It  is  impossible  to  determine  by  clinical  signs  which 
bacteria  are  present.  In  order  to  decide  this,  it  is 
necessary  to  resort  to  microscopic  and  bacteriological 
examination. 

It  is  important  for  us  to  note  that  streptococcus 
forms  of  mastitis  not  infrequently  appear  as  a  con- 
tagious disease  and  little  by  little  extend  to  a  large  pro- 
portion of  the  cows  of  the  herd.  It  is  also  important  to 
note  that  streptococci  in  certain  forms  of  mastitis  may 
continue  in  the  secretion  after  the  principal  clinical  signs 
have  disappeared,  and  are  able  to  again  cause  a  breaking 
out  of  inflammation  of  the  gland  when  lactation  begins 
anew. 

The  admixture  of  pus  gives  the  milk  a  most  unappe- 
tizing appearance,  often  causes  an  unpleasant  taste  and 
frequently  causes  it  to  putrefy  quickly,  or  to  curdle.  On 
this  account,  it  is  necessary  to  prevent  the  mixing  of  the 
secretion  from  infected  glands  with  the  other  milk.  Be- 


MASTITIS    BACTERIA  95 

sides,  it  is  highly  probable  that  the  pus  itself  may  be 
harmful  if  it  is  taken  by  small  children.  The  greatest 
weight,  however,  is  to  be  placed  on  the  possibility  that 
the  bacteria  contained  in  the  mastitis  milk  may  cause 
disease  in  man,  if  they  are  taken  into  the  digestive  canal. 
We  know  that  staphylococci  and  streptococci  which  have 
reached  the  human  digestive  canal  in  other  ways  have 
sometimes  proven  to  be  most  virulent,  and  we  may  sup- 
pose that  the  same  is  true  of  mastitiscocci  and  possibly 
also  of  the  coli-aerogenic  forms. 

Inflammation  of  the  udder  is  a  very  common  condi- 
tion of  the  cow  and,  therefore,  it  might  be  expected  that 
there  would  be  frequent  opportunity  to  observe  the 
harmful  effect  of  infected  milk  upon  man.  That  this  is 
not  the  case  may  be  due  partly  to  the  relatively  low 
virulence  of  some  of  the  mastitis  bacteria  for  man,  and 
because  it  is  only  in  the  rarest  cases  that  it  is  possible 
for  the  physician  to  gain  sufficient  information  to  trace 
the  special  disease  of  his  patient  to  the  use  of  milk,  and 
then  to  trace  this  to  a  certain  diseased  cow.  Further, 
there  is  the  fact  that  most  milk  for  small  children  is  used 
boiled,  so  that  the  bacteria  present  have,  for  the  most 
part  been  killed.13  As  examples  of  the  danger  of  using 
the  milk  from  cows  with  mastitis,  the  following  cases  of 
disease  may  be  mentioned : 

1.  In  Christiana,  in  1894,  A.  Hoist  observed  acute 
catarrh  of  the  stomach  and  intestines  in  four  adults  and 
four  children,  who  lived  in  three  separate  houses.  They 
had  all  drunk  milk  some  hours  before  the  attack.  Those 
members  of  the  household  who  had  taken  little,  or  boiled, 
milk  remained  in  good  health.  The  milk  in  question  had 
a  normal  appearance,  but  was  slightly  acid  and  con- 
tained masses  of  short  or  long  streptococci.  The  milk 

13  In  Denmark,  as  in  other  countries  of  Continental  Europe,  very 
little  raw  milk  is  fed  to  children.  [L.  P.] 


96  MILK  HYGIENE 

came  from  a  herd  in  which  a  cow  with  mastitis  was 
found,  and  it  was  explained  that  her  secretion  had  been 
mixed  with  the  common  supply  that  very  day. 

2.  Prof.  Hoist  has  also  reported  the  following  cases : 
Five  persons  were  attacked  with  acute  catarrh  of  the 
stomach  and  intestines  a  couple  of  hours  after  drinking 
milk  from  the  same  milk  shop.    The  milk  came  from  a 
herd  in  which  a  case   of  inflammation  of  the    udder, 
caused  by  streptococci,  was  discovered  by  special  inves- 
tigation. Here,  also,  it  was  shown  that  mastitis  secretion 
had  been  mixed  on  the  same  day  with  the  other  milk, 
through  the  mistake  of  a  new  servant. 

3.  Dr.  Johnnesen  observed,  likewise  in  Christiana, 
two  cases  of  diarrhoea  (mother  and  child)  which  began 
two  hours  after  the  use  of  raw  milk  which  contained 
numerous  diplococci  and  streptococci.    The  examination 
of  a  herd  that  had  furnished  the  milk  revealed  that  two 
cows  suffered  with  inflammation  of  the  udder,  and  in 
their  secretion  these  cocci  were  found.    Apparently  still 
other  cases  arose  from  the  use  of  the  same  milk,  but 
these  were  not  investigated  closely. 

4.  Four  children  of  one  family  were  attacked  with 
acute  catarrh  of  the  stomach  and  intestines,  also  a  child 
of  another  family.     The  disease,  in  both  cases,   was 
traced  to  the  same  milk.     This  appeared  by  superficial 
examination  to  be  normal,  but  by  microscopic  examina- 
tion it  was  shown  to  be  rich  in  diplo-  and  streptococci. 
Here,  also,  it  appeared  with  practical  certainty  that  the 
harmful  quality  of  the  milk  was  derived  from  a  case  of 
mastitis. 

5.  In  Stockholm  14  the  members  of  nine  families  be- 
came ill  with  the  following  symptoms:  fever,  languor, 
faintness,  nausea,  vomiting  and  diarrhoea,  together  with 

14  Zeitschrift  f iir  Fleisch  und  Milchhygiene,  x.  p.  280. 


MASTITIS  97 

cramps  in  the  legs.  The  disease  was  traced  to  the  use 
of  milk  from  the  same  herd.  This  herd  comprised  14 
cows,  one  of  which  was  proven  to  be  afflicted  with  mas- 
titis. Two  persons  working  in  the  stable  were  sick  with 
these  same  symptoms.  The  same  forms  of  bacteria  were 
found  in  the  faeces  of  the  sick  persons  that  were  found  in 
the  udder  secretion  of  the  diseased  cow. 

6.  Moro  15  has  reported  the  following  case  due  to  the 
use  of  the  milk  of  a  goat  suffering  with  a  necrotic 
inflammation  of  the  udder:  six  persons  who  had  taken 
the  milk  in  coffee  became  very  sick  one  to  two  hours 
afterward;  they  had  chills,  were  nauseated  and  had 
headache ;  11  hours  later  colic,  vomiting  and  great  thirst. 

7.  Lameris  and  van  Harrevelt 16  mention  an  outbreak 
of  diarrhrea  among  a  number  of  persons  in  a  hospital. 
The  disease  was  traced  with  comparative  certainty  to 
the  use  of  milk.    This  came  from  a  herd  in  which  several 
cases  of  streptococcus  mastitis  were  found.    The  infec- 
tion probably  came  from  the  use  of  milk  from  a  cow  that 
appeared  to  have  recovered,  but  whose  milk  still  con- 
tained streptococci.     As  the  milk  was  used  only  after 
being  boiled  it  was  thought  that  the  disease  was  really 
due  to  the  presence  of  toxins,  but  it  is  very  probable  that 
streptococci  may  have  lived  through  boiling  of  milk,  as 
tubercle  bacilli  have,  that  is  in  the  film,  froth,  scum  or 
on  the  spoon,  etc. 

An  observation  by  Edwards  and  Severn  17  seems  to 
belong  here.  It  concerns  an  epidemic  of  follicular  in- 
flammation of  the  tonsils  which  was  traced  to  the  milk, 
probably  from  one  cow,  which  contained  staphylococci 
and  streptococci,  which  bacteria  were  also  found  in  the 
coating  of  the  throat  of  the  affected  persons. 

15  Archiv  f .  Wissensch.  u.  prakt.  Tierheilkunde,  1886,  p.  411. 

16  Zeit.  f .  Fleisch  u.  Milchhyg-iene,  xi.  p.  114. 

17  British  Medical  Journal,  ii.  1897,  p.  339. 

7 


98  MILK  HYGIENE 

In  the  literature  there  are  reports  of  numerous  simi- 
lar epidemics  of  inflammation  of  the  throat  in  man 
which  had  their  origin  in  infection  through  milk,  but 
there  are  no  proofs  that  these  were  caused  by  cases  of 
mastitis.  They  may  have  come  from  a  later  contamina- 
tion of  the  milk  with  pathogenic  bacteria. 

[A  large  number  of  cases  of  this  sort  are  recorded  by 
Swithinbank  and  Newman  in  their  "  Bacteriology  of 
Milk,"  published  in  1903.  L.  P.] 

Since  cases  of  udder  inflammation  in  which  the  secre- 
tion contains  bacteria  harmful  to  man  cannot  be  differ- 
entiated by  clinical  means  from  the  less  dangerous,  the 
milk  of  every  cow  affected  with  mastitis  should  be  re- 
garded as  injurious  to  health.  This  applies  not  alone 
to  the  altered  secretion,  but  also  to  the  apparently  nor- 
mal milk  from  the  parts  of  the  udder  not  affected.  The 
diseased  secretion  will  always  soil  the  udder  and  teats, 
and  therefore  there  is  no  warranty  that  the  bacteria  in 
question  do  not  fall  into  the  milk  when  drawn  from  a 
healthy  section  of  the  udder.  This  is  true  especially 
when  the  improper  practice  is  followed  of  milking  the 
diseased  secretion  on  the  floor. 

If  a  case  of  gangrenous  mastitis  appears  in  the 
herd,  the  affected  animal  must  be  removed  from  the 
stable,  since  it  is  possible  that  the  milk  will  be  contam- 
inated with  bacteria  that  are  often  especially  virulent 
and  that  multiply  very  rapidly.  Upon  the  occurrence  of 
infectious  inflammations  of  the  udder  in  a  milch  herd  it 
may  be  necessary  to  forbid  the  sale  of  milk  that  is  not 
boiled.  Milk  from  a  herd  affected  with  this  disease 
should  never  be  used  as  ' '  nursery  milk. ' ' 

i.  Acute  croupous  and  hemorrhagic  enteritis.  Some- 
times a  virulent  enteritis  occurs  among  young  cattle ;  it 
appears  less  often  among  mature  cattle ;  it  may  appear 
as  a  sporadic  disease  or  as  a  smal1  :pidemic.  This  dis- 


INFECTION  BY  MILK  99 

ease  is  accompanied  by  fever  and  signs  of  great  consti- 
tutional disturbance,  and  it  quite  often  ends  in  death. 
The  pathological  changes  have  been  studied  compara- 
tively little  up  to  this  time.  It  may,  however,  be  stated 
that  there  is  sometimes  found  a  diffuse  inflammatory 
hyperaemia  in  the  mucous  membrane  of  the  whole  small 
intestine,  sometimes  very  extensive  pseudo-membranes 
form  a  cast  within  the  intestine,  while  in  other  cases 
swelling  and  hemorrhagic  infiltration  of  Peyer's  patches 
are  found  which,  at  the  same  time,  may  be  ulcerated,  or 
covered  with  crupo-diphtheritic  exudate.  The  mesen- 
teric  glands,  usually  other  glands,  too,  are  swollen  and 
more  or  less  hypersemic,  or  even  hemorrhagic ;  the  spleen 
may  be  enormously  swollen.  In  some  cases  the  lesions 
somewhat  resemble  typhoid  fever  in  man,  yet  the  disease 
is  not  identical  with  it. 

The  investigations  that  have  been  made  by  Jensen 
indicate  that  these  forms  of  enteritis  are,  as  a  rule, 
caused  by  bacteria  which  belong  to  the  hog  cholera  group 
and  that  are  therefore  closely  related  to  the  typhoid 
bacillus.  The  flesh  of  the  infected  animals  may  be  most 
dangerous  to  health;  not  a  few  of  the  so-called  "  meat 
poisoning,"  epidemics  have  been  traced  directly  to  these 
forms  of  enteritis,  and  most  of  the  bacteria  isolated  in 
meat  poisoning  cases  belong  to  the  hog  cholera  group. 

It  is  not  impossible  that  in  virulent  enteritis  bacteria 
that  have  entered  the  blood  may,  now  and  then,  be 
excreted  in  the  milk  as,  for  example,  when  there  are 
slight  hemorrhages  in  the  udder  tissue;  doubtless, 
however,  a  serious  contamination  may  occur  during 
milking,  for  in  this  disease  diarrhoea  is  a  prominent 
symptom  and  the  afflicted  animals  are  much  soiled  by 
their  fasces. 

A  positive  example  of  the  transmission  of  such  a 
form  of  enteritis  to  man  through  milk,  has  been  given 


100  MILK  HYGIENE 

by  Follenius  and  Gaffky.18  It  is  as  follows  :  In  the  lab- 
oratory of  hygiene  at  Giessen,  two  assistants  and  a  ser- 
vant became  very  ill  after  drinking  raw  milk  which  was 
proven  to  have  come  from  a  cow  with  hemorrhagic  ente- 
ritis. The  symptoms  were  headache,  weakness  and  diar- 
rhrea.  In  the  servant,  the  disease  seemed  to  resemble 
cholera,  with  the  others  it  was  more  like  typhoid  fever. 
Gaffky  isolated  from  the  faeces  of  the  sick  persons,  as 
well  as  from  the  faeces  of  the  cow,  a  member  of  the  colon 
group  which  grew  rapidly  and  was  very  virulent.  The 
organism  was  the  same  in  all  cases. 

It  is  probable  that  a  case  of  disease  mentioned  by 
Eehn,19  was  caused  in  a  similar  way.  A  child  two  and  a 
quarter  years  old  was  attacked  by  a  typhoid-like  disease 
after  drinking  raw  milk,  ivhich  ivas  rich  in  colon  bacilli. 
He  recovered  in  the  course  of  five  weeks.  A  sister  some- 
what older  had  a  lighter  attack. 

As,  doubtless,  every  case  of  such  virulent  enteritis 
of  cattle  offers  opportunity  for  the  infection  of  the  milk 
with  pathogenic  bacteria,  which  apparently  are  virulent 
for  man,  every  animal  affected  with  a  severe,  bloody  or 
febrile  diarrhoea,  should  be  removed  from  the  stable  at 
once.  The  contaminated  part  of  the  stable  should  be 
carefully  cleansed  and  disinfected.  If  a  number  of  cases 
of  the  disease  occur,  the  sale  of  the  milk  of  the  whole 
herd  must  be  prohibited,  for  a  longer  or  shorter  time. 

In  this  connection,  observations  by  A.  Hoist 20  con- 
cerning cases  of  poisoning  through  "  pultost  "  (a  kind 
of  cheese)  should  be  mentioned,  since  the  bacillus  found 
belongs  to  the  same  group,  although  it  is  not  proven  that 
its  occurrence  in  the  cheese  was  due  to  contamination 
with  bacteria  from  cases  of  enteritis  of  cattle. 

18  Ref.  in  the  Zeitsch.  fiir  Hygiene,  III. 
19Hygien.  Rundschau,  IV,  No.  21. 
20  Zentralblat  fiir  Bact,  XX,  1896. 


INFECTION  BY  MILK  101 

Indigestion  of  cows  very  often  leads  to  a  lessening  of 
milk  secretion  and,  at  the  same  time,  to  a  change  in  its 
taste  and  composition.  The  milk  may  have  a  bitter  or 
salty  taste  and  appear  to  be  thinner,  is  sometimes  yel- 
lowish in  color  and  coagulates  very  easily.  When  such 
changes  are  present,  or  when  there  is  simply  a  disturb- 
ance of  digestion,  the  milk  should  not  be  mixed  with 
other  milk  designed  for  sale.  The  question  here  is  not, 
however,  one  of  the  contaminating  micro-organisms,  nor 
does  it  relate  strictly  to  the  passage  of  a  disease  from 
cattle  to  man. 

j.  "  Calf  cholera."  It  is  well  known  that  under  this 
common  term  are  grouped  infections  of  the  intestines 
(usually  caused  by  colon  bacilli,  less  often  by  proteus 
forms)  and  umbilical  infection,  with  or  without  local 
inflammation,  (arthritis,  pyaemic  processes,  bacterise- 
mia)  ;  the  latter  infection  is  sometimes  caused  by  colon 
forms,  sometimes  by  staphylococci  and  streptococci  and, 
rarely,  by  necrosis  bacilli  or  other  bacteria. 

An  endemic  outbreak  of  these  infectious  diseases 
signifies  a  great  propagation  of  the  causative  bacteria 
in  the  cow  stable  and,  therefore,  it  is  most  probable  that 
the  milk  becomes  infected  while  being  drawn.  There  are 
no  positive  cases  that  prove  that  milk  from  a  farm  where 
calf  cholera  is  prevalent,  has  caused  disease  of  children 
or  adults,  but  as  no  special  attention  has  been  given  to 
this  matter,  it  is  quite  natural  that  such  cases  as  may 
occur  are  not  fully  understood.  Milk  from  such  a  herd 
should  be  regarded  as  suspicious  and  its  sale  as  '  *  nurs- 
ery milk  ' '  should  not  be  allowed  until  conditions  on  the 
farm  have  been  improved. 

k.  Septic  metritis.  In  septic  inflammation  of  the 
uterus,  which  is  specially  prevalent  in  herds  where  cows 
in  calf  are  purchased  from  dealers,  great  quantities  of 
ichorous  exudate  are  secreted  and  expelled  from  the 


102  MILK  HYGIENE 

vagina,  and  this  exudate  contains  pathogenic  bacteria 
(streptococci,  staphylococci,  colon  forms,  etc.)  as  well 
as  bacteria  of  putrefaction  (proteus  varieties  among 
them).  During  milking,  some  of  this  pathological  mate- 
rial may  fall  directly  into  the  milk  and  the  udder,  tail, 
thighs  and  flanks  are  usually  so  dirty  that  contamination 
of  the  milk  is  scarcely  avoidable.  There  are  no  definite 
observations  of  disease  that  has  been  caused  in  man 
through  the  milk  of  such  animals,  but  since  these  organ- 
isms are  known  to  be  harmful  there  can  be  no  doubt  that 
the  milk  may  be  injurious  to  health;  therefore,  its  use 
should  not  be  permitted  under  any  conditions.  Since  it 
is  readily  possible  that  the  cows  standing  beside  the  af- 
fected animals  are  contaminated  by  the  excretions  from 
the  uterus,  sick  animals  should  not  be  allowed  to  remain 
in  the  stable  occupied  by  the  milk  producing  herd. 

The  same  applies  to  cows  which  retain  the  afterbirth, 
but  without  suffering  from  septic  metritis.  The  danger 
of  contamination  with  pathogenic  bacteria  in  this  case 
is  not  great  but  the  milk  may  be  contaminated  very 
easily  by  the  entrance  into  it  of  the  bacteria  of  putre- 
faction that  are  present  in  the  purulent  discharges. 
Moreover,  the  milk — even  that  of  healthy  animals — may 
absorb  foul  odors  during  milking,  odors  which  are  often 
very  pronounced  throughout  the  whole  stable  where  such 
an  animal  is  stalled ;  or  the  odor  of  carbolic  acid  or  creo- 
lin  used  for  treating  the  animal  may  enter  the  milk. 
Hence,  such  cows  should  be  taken  to  an  isolated  part  of 
the  stable  where  other  cows  cannot  come  in  contact  with 
them  and  their  milk  should,  under  no  circumstances,  be 
added  to  the  market  milk. 

I.  Suppurative  processes.  What  has  been  said  of 
septic  metritis  applies,  essentially,  to  diffuse  cellulitis 
and  extensive  suppurating  sores.  When  animals  with 
such  conditions  are  in  the  stable,  there  is  great  danger 


INFECTION  BY  MILK  103 

that  the  milk  may  be  infected  with  bacteria  of  suppura- 
tion, among  which  streptococci  are  able  to  cause  enteritis 
in  man.  With  wounds  and  ulcerations  of  the  teats  (pox, 
gangrenous  buckwheat  eruption,  etc.),  the  danger  is 
present  and  the  milk  of  such  cows  should,  at  least,  not  be 
used  for  nursery  milk.  If  there  are  single  small  sores 
that  no  longer  suppurate,  the  milk  may  be  sold,  pro- 
vided the  teats  are  carefully  washed  before  milking. 

m.  Other  infectious  diseases.  The  secretory  function 
of  the  milk  glands  is  affected  to  no  small  degree  in  many 
severe  infectious  diseases.  This  is  shown  principally  by 
the  diminished  quantity  of  milk  but  often,  at  the  same 
time,  by  changes  in  its  composition.  In  this  way  the 
milk  may  acquire  an  unpleasant  or  salty  taste ;  its  layer 
of  cream  has  often  a  dirty  color  and,  when  it  is  boiled, 
little  lumps  separate  due  to  the  increased  quantity  of 
albumin  or  globulin.  It  is  probable  that  under  these  con- 
ditions abnormal  products  of  metabolism  and,  now  and 
then,  pathogenic  bacteria  find  their  way  into  the  milk; 
therefore,  milk  should  not  be  used  in  severe  cases  of 
fever,  as  rinderpest,  malignant  catarrhal  fever,  croup, 
malignant  broncho-pneumonia,  pysemic  and  septicsemic 
processes,  etc. 

n.  Milk  sickness.  A  curious  disease  called  "  milk 
sickness  "  is  found  in  the  central  part  of  the  United 
States ;  it  was  formerly  confused  with  anthrax,  and  has 
occurred  as  an  epidemic  among  animals  and  man  but 
seems  to  disappear  with  improved  cultivation.  Accord- 
ing to  the  reports  of  Dr.  Kimmell  the  disease  occurs 
among  horses  and  ruminants,  when  they  are  pastured  in 
certain  places.  After  a  period  of  incubation,  violent 
trembling  and  great  restlessness  appear  which  increase 
during  the  succeeding  days.  The  animal  may  fall  and 
die  suddenly  but  often  it  lies  for  several  days  in  a  para- 
lyzed, half  dead  condition.  Through  the  ingestion  of 


104  MILK  HYGIENE 

meat,  milk  and  dairy  products,  the  disease  is  communi- 
cable to  man.  It  may  develop  mildly  with  severe  vomit- 
ing and  difficult  breathing  as  the  prominent  symptoms, 
or,  on  the  other  hand,  it  may  end  in  death,  preceded  by 
subnormal  temperature,  paralysis  of  a  great  part  of  the 
body  and  progressive  dyspnoea.  Death  approaches 
imperceptibly  and  without  the  supervention  of  rigor 
mortis.  This  mysterious  disease,  which  was  formerly 
attributed  to  poisonous  plants  eaten  by  the  cattle  with 
their  food  and  whose  toxic  principles  were  supposed  to 
be  secreted  in  the  milk,  is  probably,  according  to  the  pre- 
ceding, an  infectious  disease. 

V.    CONTAMINATION  WITH  ORGANISMS  OF 
SPECIFIC  DISEASES  OF  MAN 

Milk  may  be  contaminated  with  specific  organisms 
from  persons  suffering  with  infectious  diseases.  Such 
contamination  may  take  place  during  milking,  during  its 
handling  on  the  farm  or,  later,  while  it  is  being  handled 
or  stored  in  the  dairy  or  market-place.  Sometimes  this 
occurs  from  sick  persons  coming  directly  into  contact 
with  the  milk,  sometimes  it  occurs  in  an  indirect  way. 
The  method  of  contamination  differs  in  respect  to  dif- 
ferent diseases,  since  infectious  material  may  come  not 
only  directly  or  indirectly  from  persons  but  may  also 
come  from  the  water  used  for  cleansing  the  milk  vessels. 

In  the  literature  of  recent  years,  there  are  numerous 
reports  of  very  significant  epidemics  supposed  to  be  due 
to  infection  carried  by  milk.  Such  "  milk  epidemics  ' 
are  especially  frequent  in  England  and  America  and  this 
may,  no  doubt,  be  accounted  for  by  the  fact  that  it  is 
not  so  customary  in  England  and  America  to  boil  milk 
as  it  is,  for  example,  in  Denmark  and  Germany.  Most 
of  the  epidemics  relate  to  typhoid  fever,  diphtheria  and 
scarlet  fever ;  but  cholera  and  several  other  diseases  may 


CONTAMINATION  WITH  ORGANISMS     105 

be  spread  by  means  of  milk.  In  some  cases,  no  doubt, 
epidemics  have  wrongly  been  ascribed  to  the  use  of  milk, 
for  their  origin  might  be  explained  in  another  way,  but 
a  very  great  number  of  cases  remain  wherein  the  respon- 
sibility of  milk  as  a  distributor  of  contagion  cannot  be 
doubted. 

[In  most  cases,  the  conclusion  that  a  given  outbreak 
of  disease  is  caused  by  the  use  of  infected  milk  does  not 
rest  on  the  evidence  of  the  discovery  of  the  specific 
organism  in  the  milk,  but  on  the  manner  in  which  the 
outbreak  occurs  and  upon  the  various  attendant  circum- 
stances. For  this  there  are  two  reasons ;  first,  none  of 
the  specific  germs  may  be  present  in  the  drop  or  two  sub- 
jected to  examination,  even  though  they  are  relatively 
numerous  in  the  whole  supply,  for  such  organisms  are 
not  in  solution  and  are  not  evenly  distributed  and,  sec- 
ond, infectious  diseases  do  not  occur  until  after  a  certain 
period  of  incubation,  and  when  this  time  has  elapsed  the 
milk  that  carried  the  specific  organisms  is  no  longer  in 
existence.  But  the  evidence  of  the  transfer  of  such  dis- 
eases by  milk  is  none  the  less  convincing.  It  is  as  clear, 
for  example,  as  the  evidence  that  typhoid  fever  is  car- 
ried by  contaminated  water,  and  this  evidence  is  re- 
garded as  sufficient  to  justify  the  expenditure  by  cities 
of  vast  sums  to  secure  pure  water. 

Milk  epidemics  are  often  characterized,  according  to 
the  observations  of  Swithinbank  and  Newman21  by  the 
following  features : 

1.  Special  incidences  of  disease,  as  among  the  cus- 
tomers of  a  certain  milkman ;  in  families  using  the  great- 
est quantities  of  milk;  among  persons  who  drink  most 
milk  and,  for  this  reason,  among  women  and  children. 

2.  A  relatively  short  period  of  incubation. 

21  The  Bacteriology  of  Milk,  London,  1903. 


106  MILK  HYGIENE 

3.  Sudden  onset  and  rapid  decline  of  the  outbreak. 

4.  Certain  clinical  characteristics  of  the  milk-borne 
disease,  especially  a  somewhat  milder  form  of  disease 
than  is  customary. 

5.  A  lower  mortality  rate  than  when  the  disease  is 
transmitted  by  other  means,  as  shown  by  the  following 
table : 


DISEASE 

MORTALITY  ] 

PERCENTAGES 

Milk-Borne  Outbreaks 

Not  Milk-Borne 

Scarlet  fever  

12.0 

1(5.2 

Typhoid  fever  

11.0 

17.4 

Diphtheria  . 

18.9 

30.3 

The  above  table  is  made  by  Swithinbank  and  New- 
man (whose  chapters  on  this  subject  should  be  read) 
from  a-  study  of  many  thousands  of  cases  of  milk-borne 
disease.  It  should  be  stated  that  the  mortality  percent- 
ages in  the  first  column  are  actual,  and  taken  from  the 
records,  while  those  of  the  second  column  are  based  on 
estimates  from  other  writers.  L.P.] 

a.  Typhoid  fever.  During  recent  years,  especially, 
there  have  been  numerous  reports  from  city  and  coun- 
try, of  typhoid  epidemics  which  have  been  traced  to  con- 
tamination of  the  milk  by  typhoid  bacilli,  and  to  the  dis- 
semination of  disease  through  such  milk.  At  first,  the 
correctness  of  the  observations  was  doubted,  since  it 
was  not  possible  to  find  the  typhoid  bacillus  in  milk,  but 
recently  the  observations  have  so  increased  in  number 
and  accuracy  that  it  is  not  to  be  denied  that  the  principal 
means  by  which  typhoid  fever  is  distributed  in  places 
ivhere  there  is  a  safe  and  hygienic  water  supply,  is 
through  the  milk.  Although  it  cannot  be  said  that 
typhoid  fever  is  especially  prevalent  in  Denmark,  yet  a 


TYPHOID  FEVER  107 

number  of  epidemics  during  recent  years,  may  be  pointed 
out  that  can  be  traced  with  more  or  less  certainty  to 
infection  through  milk,  or  with  which  milk  was  con- 
cerned in  the  great  spread  of  the  contagion.  Dr.  Caroe 22 
has  reported  about  90  large  and  small  typhoid  epidemics 
which  occurred  outside  of  Copenhagen  during  the  period 
from  1878-96  and  which  probably  were  due  to  infection 
from  milk,  also  5  milk  epidemics  which  occurred  in 
Copenhagen  during  the  years  1879-1895.  In  1900,  no 
less  than  3  milk  epidemics  occurred  in  Copenhagen,  and 
it  does  not  appear  that  these  were  related  to  each  other. 
The  sanitary  inspector,  A.  Ulrik,23  made  a  detailed  re- 
port on  these  outbreaks,  and  since  they  show  very  char- 
acteristically the  conditions  that  occur  in  milk  epidem- 
ics, they  are  cited  as  examples. 

In  the  first  epidemic,  the  cases  were  grouped  about 
a  city  milch  herd  and  the  two  sales  places  connected 
with  it.  Some  cases  of  typhoid  appeared  in  this  quar- 
ter of  the  city  in  August,  but  the  origin  of  these  was  not 
perfectly  clear.  At  this  time,  a  saleswoman  in  charge 
of  one  of  the  milk  shops  became  ill  of  typhoid  fever  and 
was  taken  to  the  hospital.  It  was  discovered  that  she 
had  suffered  with  severe  diarrhoea  for  about  fourteen 
days  but  she  had  not  been  under  the  physician's  care 
until  high  fever  developed.  By  degrees,  35  cases  in  all 
broke  out,  among  them  the  woman  in  charge  of  the  other 
milk  shop  and  these  cases  were,  in  part,  traced  directly 
to  infective  milk ;  in  part  they  must  have  originated  from 
contagion  carried  from  one  person  to  another.  It  was 
found  during  the  time  that  the  disease  prevailed  that  the 
milk  had  twice  been  infective — at  the  beginning  and  in 
the  middle  of  August — but  it  was  not  possible  to  prove 
the  exact  channel  through  which  bacilli  entered. 

-  Tidsskrift  for  Sundhespleje,  VI,  1898. 
23Tiddskrift   for  Sundhespleje,  VIII,  1901. 


108  MILK  HYGIENE 

The  state  of  health  of  the  herd  and  the  condition  of 
cleanliness  of  the  premises  aroused  no  suspicion.  After 
cleansing  and  disinfecting  and  after  discontinuing  the 
business  for  a  short  period,  the  epidemic  ceased  at  once, 
although  a  few  individual  cases  still  occurred  that  were 
caused  by  infection  that  had  taken  place  earlier. 

The  milk  of  these  same  shops  was  infected  anew 
in  the  middle  of  October,  probably  by  a  girl  who  was 
believed  to  have  become  infected  during  a  stay  in  a  place 
near  Copenhagen.  Shortly  afterward,  the  two  sons  of 
the  herdsman  were  infected  by  the  milk,  and  later  three 
other  persons.  By  means  of  a  temporary  prohibition 
of  the  sale  of  raw  milk  and  raw  cream  from  the  herd  and 
by  thorough  cleansing,  the  epidemic  was  checked. 

The  third  epidemic  was  of  greater  extent.  In  the 
middle  of  November  a  number  of  typhoid  cases  were 
found  in  a  certain  section  of  the  city  and  suspicion  soon 
fell  on  a  certain  milk  shop.  The  further  development  of 
the  epidemic,  during  which  the  shopkeeper  became  ill, 
confirmed  these  suspicions.  Altogether,  71  persons  were 
infected  directly  or  indirectly  through  the  milk,  which 
must  have  been  most  contaminated  from  October  26th  to 
November  1st,  judging  from  the  times  of  appearance 
of  disease  and  the  number  of  persons  affected.  Despite 
the  investigation  which  was  instituted,  the  ultimate  ori- 
gin of  the  infection  was  not  discovered. 

H.  Moller  has  observed  and  described  as  follows  an 
epidemic  caused  by  milk  from  a  cooperative  dairy,  which 
is  rather  characteristic : 24  Seven  farms  supported  a 
cooperative  dairy.  A  case  of  typhoid  fever  occurred  on 
one  of  the  farms ;  the  dairy  continued  to  receive  the  milk 
but  did  not  boil  the  skim  milk  that  was  returned.  With 
brief  intermissions,  40  persons,  altogether,  became  in- 

24Ugeskrift  for  Laeger,  1890,  p.  128. 


TYPHOID    FEVER  109 

fected  with  typhoid  fever  on  the  dairy  farm  first 
infected,  on  the  farm  upon  which  the  creamery  was  sit- 
uated and  on  4  other  farms,  only  one  farm  remaining 
exempt.  Through  contagion,  the  disease  was  carried 
from  these  farms  to  7  other  families  and  14  more  per- 
sons became  affected. 

Hart's  and  Freeman's  collections  of  the  milk  epi- 
demics in  the  literature  gave  an  idea  of  the  importance 
of  this  method  of  transmission  of  typhoid  fever.  Hart 
collected  the  established  milk  epidemics  from  1857-81 
and  found  accounts  of  51,  with  3500  cases  of  the  disease 
and  350  deaths,  while  Freeman  found  53  epidemics  from 
1880-96.  The  number  of  milk  epidemics  observed  since 
then  is  proportionately  greater,  no  doubt  because  this 
means  of  transmission  is  better  known  and,  therefore,  is 
more  frequently  recognized  than  before. 

While  in  the  case  of  some  epidemics  it  is  quite  easy 
to  prove  that  the  infection  of  the  milk  came  from  a  sick 
person  working  with  the  milk,  in  other  cases  everything 
points  to  the  producing  farm  as  the  seat  of  infection,  but 
may  not  reveal  the  ultimate  origin  of  the  contagion.  In 
such  cases  attempts  have  been  made  to  trace  the  infec- 
tion to  a  disease  of  the  cows,  but  without  sound  basis, 
for  no  instance  is  known  wherein  domestic  animals  have 
suffered  from  any  disease  caused  by  the  typhoid 
bacillus. 

From  our  knowledge  of  the  epidemiology  of  typhoid 
fever,  it  may  be  said  with  assurance  that  milk  may  be 
infected  with  typhoid  bacilli  through  the  addition  of 
water  (in  washing  the  vessels  or  through  adulteration 
with  water)  or  by  bacteria  from  patients  or  conva- 
lescents. 

It  is  a  well  known  fact  that  many  epidemics  of  this 
disease  have  been  traced  to  infection  from  impure  drink- 
ing water,  and  it  is  self  evident  that  milk,  which  is  favor- 


110  MILK  HYGIENE 

able  to  the  growth  of  typhoid  bacilli,  may  be  infected  in 
this  way.  Water  from  open  or  thin  walled  springs  or 
wells  may  be  directly  infected  by  the  entrance  of  water 
which  has  been  contaminated  by  the  excretions  of  the 
sick.  [All  surface  streams  are  liable  to  become  contam- 
inated either  directly  or  indirectly,  through  carelessness 
or  imperfect  drainage  systems. 

Typhoid  bacilli  may  be  blown  about  in  dust,  car- 
ried on  the  boots  of  persons  who  walk  over  infected  sur- 
faces and  they  may  also  be  carried  by  flies,  as  was 
abundantly  proven  during  the  Spanish- American  and 
the  South  African  wars.  Cloths  used  for  washing  milk 
cans  may  carry  this  infection.  In  one  instance,  in  Phila- 
delphia, it  was  found  that  a  small  milk  dealer  was  in  the 
habit  of  washing  his  milk  bottles  in  the  family  wash  tub. 
Milk  has  become  contaminated  during  cooling,  either  by 
a  leak  in  the  tubular  cooler  or  by  the  entrance  of  water 
into  a  submerged  can.  L.  P.] 

Concerning  direct  or  indirect  infection  from  sick  per- 
sons or  convalescents,  emphasis  should  be  laid  upon  the 
fact  that  the  disease  often  runs  so  light  a  course  that  the 
diagnosis  of  typhoid  fever  is  not  established;  further, 
that  faeces,  and  often  urine,  contain  bacilli  in  great  num- 
ber and  that  convalescents  often  have  bacteriurea  for 
months  after  typhoid  fever  and  daily  excrete  number- 
less bacilli  with  the  urine.  Neufeld 25  has  collected  some 
reports  on  this  subject :  of  210  typhoid  patients  not  less 
than  45  (more  than  20%)  excreted  bacilli  with  the  urine, 
and  Petruschky 26  found  that  the  number  of  bacilli  in  the 
urine  exceeded  170,000,000  per  c.c.  It  will  be  evident 
to  every  one  who  is  familiar  with  existing  conditions  and 
customs,  especially  in  the  country,  that  under  these 
circumstances  no  extreme  or  unusual  carelessness  or 

25  Deutches  med.  Wochenschr.,  1890,  p.  824. 

26  Zentralbl.  f .  Bakteriologie,  XXIII,  1898,  No.  14. 


TYPHOID    FEVER  111 

accident  is  necessary  to  afford  an  indirect  or  direct 
means  of  carrying  typhoid  bacilli  into  the  water  or  milk. 

The  typhoid  bacillus  can  multiply  rapidly  in  milk 
and  greatly  increase  in  number  in  the  course  of  a  short 
time,  it  resists  the  commencement  of  acid  formation  but 
is  partly  checked  and  killed  by  great  acidity;  yet  it  is 
not  certainly  killed  by  the  degree  of  scouring  to  which 
cream  is  subjected  before  churning.  Bolley  and  Field 
have  found  that  typhoid  bacilli  will  live  at  least  ten  days 
in  butter  [and  Bruck  has  shown  that  they  were  virulent 
after  27  days].  Hence,  not  only  milk  and  cream  but 
also  buttermilk  (epidemic  in  Hamburg;  Frankel  and 
Koster),  newly  made  butter  and  fresh  cheese  may  be 
bearers  of  virulent  typhoid  bacilli.  The  typhoid  bacillus 
is  destroyed  by  pasteurization  at  80°  C.  (176°  F.)  and 
heating  for  a  few  minutes  at  70°  to  75°  C.  (158°  to  167° 
F.)  will  kill  it.  Care  must  be  taken  to  heat  the  whole 
volume  of  milk  to  this  temperature.  (See  "  Pasteuri- 
zation.") 

In  pure  culture,  the  typhoid  bacillus  does  not  change 
the  appearance  of  milk  and  alters  its  reaction  but  little. 
It  is  very  difficult  to  detect  it  in  milk,  as  it  is  in  drinking 
water,  for  its  colonies  in  gelatin  are  very  similar  to 
those  of  the  colon  bacilli.  To  detect  it,  the  milk  must  be 
sown  in  the  usual  method  in  gelatin  plates  and  then  as 
great  a  number  as  possible  of  suspicious  colonies  iso- 
lated. These  are  then  implanted  in  fermentation  bulbs 
in  bouillon,  some  of  which  contain  grape  sugar  and  some 
sugar  of  milk.  Those  forms  which  cause  an  acid  reac- 
tion in  the  milk  sugar  bouillon  or  those  which  ferment 
the  grape  sugar  with  the  formation  of  gas  or  which  do 
not  change  the  reaction  of  the  grape  sugar  bouillon  are 
to  be  rejected.  Only  those  cultures  which  give  a  strong 
acid  reaction  without  producing  gas  in  the  grape  sugar 
bouillon,  are  really  suspicious  and  these  must  be  sub- 


112  MILK  HYGIENE 

jected  to  a  far  more  searching  examination  before  they 
can  be  identified  as  typhoid  bacilli.27  It  is  unnecessary  to 
pursue  this  subject  further,  since  the  demonstration  of 
the  typhoid  bacillus  in  market  milk  is  not,  as  yet,  a  prac- 
ticable procedure  in  milk  inspection. 

Jensen's  investigations  have  shown  that  there  are 
several  kinds  of  typhoid  bacilli,  distinguished  from  each 
other  by  a  somewhat  different  fermentative  power.  It 
appears  to  be  possible  that  by  means  of  cultures  from 
different  patients  one  may  determine  what  cases  of 
typhoid  belong  to  one  and  the  same  epidemic. 

b.  Diphtheria.  Diphtheria  not  infrequently  appears 
to  be  spread  by  milk  from  milk  shops  or  by  that  deliv- 
ered from  cooperative  dairies,  but  less  frequently  than 
typhoid  fever. 

N.  Flindt 28  has  given  a  detailed  account  of  such  an 
epidemic  in  the  neighborhood  of  Holbeak  in  which  the 
disease  was  being  spread  for  a  long  time  by  milk  from 
a  cooperative  dairy.  He  states :  The  epidemic  occurred 
in  June,  1889,  and  soon  became  violent.  Fifty-one  per- 
sons were  sick  at  the  end  of  the  month,  16  cases  occurred 
the  following  month  and  in  August  and  September  6 
more ;  3  patients  died.  Everything  tended  to  prove  that 
milk  delivered  from  the  cooperative  dairy  had  contained 
the  contagion  and  this  belief  was  strengthened  by  the 
fact  that  two  persons  from  the  dairy  were  affected.  The 
exact  mode  of  entrance  of  the  infectious  material  into 
the  milk  was  not  traced.  The  case  is  remarkable  in  that 
the  milk  appears  to  have  been  contaminated  for  quite  a 
long  period. 

-7  C.  0.  Jensen :  On  Vanskelighederne  ved  Typhusbacillens  Diag- 
nose og  om  Racer  af  Typhusbacillen.  (On  the  Difficulties  of  Diag- 
nosing Typhoid  bacilli  and  on  the  Races  of  Typhoid  bacilli) 
Hospitalstidende,  1901,  p.  1193. 

28  Ugeskrift  for  Laeger,  1890,  p.  405. 


DIPHTHERIA  113 

A  large  epidemic  of  diphtheria  29  which  broke  out 
among  the  inhabitants  of  the  villages  along  the  coast 
north  of  Copenhagen,  in  1881,  offered  conditions  of  prop- 
agation which  strongly  signified  that  milk  was  the  means 
of  spreading  the  contagion. 

In  1893  a  small  epidemic  was  noted  in  Lund,  Sweden, 
when  eight  persons  in  different  families  were  sick  with 
diphtheria.  These  cases  were  traced  to  the  use  of  milk 
from  a  farm  near  Lund  which  was  infected  with  diph- 
theria.30 

Quite  an  extended  epidemic  occurred  in  1886  in  Frim- 
ley,  England;  in  the  course  of  a  few  days  70  cases  of 
diphtheria  occurred,  distributed  in  more  than  30  fam- 
ilies, 15  cases  being  fatal.  All  the  sick  had  received  milk 
from  the  same  dairy.  Not  one  case  of  diphtheria  oc- 
curred during  this  time  among  those  using  milk  from 
other  dairies.31 

[The  medical  literature  of  recent  years  contains 
many  reports  of  milk-borne  outbreaks  of  diphtheria,  a 
number  of  which  are  gathered  and  summarized  by 
Swithinbank  and  Newman.32  The  following  case,  cited 
in  their  summary,  is  instructive.  At  Ashtabula,  Ohio, 
100  persons  became  affected  with  diphtheria  in  Decem- 
ber, 1894.  The  houses  in  which  the  disease  occurred 
were  widely  separated  but  milk  was  taken  at  all  of  them 
from  the  same  dairyman.  On  the  farm  of  this  dairyman, 
a  workman  had  a  very  sore  throat,  probably  diphthe- 
ritic. This  person  had  assisted  in  the  work  of  the  dairy 
while  suffering  acutely  from  sore  throat.  Of  44  house- 
holds investigated,  it  was  found  that  32  had  received 

29  Ugeskrift  for  Laeger,  1881. 

30  Hospitalstidende,  1893. 

31Ref.  in  Milchzeitung,  1886,  p.  835. 
32  Bacteriology  of  Milk. 

8 


114  MILK  HYGIENE 

milk  directly  from  this  sick  person;  the  other  12  had 
received  milk  from  the  same  dairy  but  it  had  been  deliv- 
ered by  another  man.  In  this  outbreak  there  were  24 
deaths.  L.P.]  A  great  many  other  reported  cases 
might  be  quoted. 

As  yet  the  diphtheria  bacillus  has  rarely  been  iso- 
lated from  market  milk  but,  notwithstanding  this,  there 
can  be  no  doubt  of  its  occurrence  in  milk  and  that  it  may 
thus  cause  epidemics  like  those  mentioned  above.  The 
bacillus  must  come  directly  or  indirectly  from  the  oral 
cavity  of  people  who  are  or  have  been  recently  attacked 
by  diphtheria.  Just  as  the  typhoid  bacillus  is  main- 
tained in  many  cases  in  the  urine  of  convalescents,  it  is 
also  very  common  for  diphtheria  bacilli  to  retain  life  for 
months,  even  for  a  whole  year,  in  the  oral  cavity  and 
on  the  mucous  membrane  of  the  nose  in  persons  who 
have  been  affected,  but  who  have  entirely  recovered  from 
the  disease.  It  is  on  this  account  that  it  was  possible  in 
only  a  few  epidemics  of  milk-borne  diphtheria  to  dis- 
cover the  original  source  of  infection  and  it  is  difficult, 
not  to  say  impossible,  to  wholly  guard  against  the  occa- 
sional infection  of  milk  by  diphtheria  bacilli.  Fortun- 
ately, these  bacilli  are  frequently  of  low  virulence. 

The  opinion,  that  was  held  formerly  by  some,  that 
diphtheria  in  man  could  come  from  a  disease  of  milch 
cows,  is  entirely  erroneous. 

It  has  been  stated  that  diphtheria  bacilli  grow  readily 
in  raw  milk  and  that  they  thrive  less  well  in  boiled  milk 
(Schottelius) ;  but  from  the  experiments  made  by  Meyer, 
it  appears  that  diphtheria  bacilli  act  as  other  bacilli ;  that 
is,  that  they  are  checked  by  the  germicidal  power  of 
fresh  raw  milk  and  grow  best  in  boiled  milk. 

Diphtheria  bacilli  withstand  acidity  and  may  there- 
fore be  present  in  the  different  dairy  products,  but  the 
infectivity  of  the  latter  has  not  yet  been  determined. 


SCARLET  FEVER  115 

It  is  certainly  very  difficult  to  prove  the  presence  of 
diphtheria  bacilli  in  market  milk  because  even  if  the 
milk  has  been  the  cause*  of  the  epidemic,  they  are  pres- 
ent in  only  very  small  quantity  and,  usually,  but  for  a 
limited  time.  If  one  wishes  to  experiment  in  this  direc- 
tion the  best  method  of  proceeding  is  to  make  a  culture 
on  blood  serum  (Loffler's)  in  a  manner  similar  to  that 
employed  in  the  examination  of  the  throat  of  a  diph- 
theritic patient.  If  the  culture  tubes  are  brought  to 
body  heat  for  24  hours,  the  conditions  will  be  more 
favorable  for  the  increase  of  the  diphtheria  bacilli 
than  for  the  greater  number  of  milk  bacteria.  One 
must  then  make  a  careful  study  of  the  colonies  that  have 
developed. 

c.  Scarlet  fever.  Reports  of  scarlet  fever  epidemics 
that  are  presumably  to  be  attributed  to  the  spread  of 
infection  through  the  milk,  come  chiefly  from  England 
and  America.  The  infectious  material  must  come  from 
affected  persons  and  may  enter  the  milk  directly  through 
their  contact  with  it  when  it  is  being  drawn,  in  the  sales- 
places,  etc.,  or  it  may  reach  the  milk  in  an  indirect  way. 
Since  the  organism  of  this  disease  is  unknown,  it  is  diffi- 
cult to  form  a  well  founded  opinion  concerning  these 
possibilities,  and  one  cannot  ascertain  whether  there  is 
an  increase  of  the  infectious  material  in  milk. 

About  18  years  ago  some  scarlet  fever  epidemics 
aroused  great  attention  in  England  because  it  was 
thought  that,  without  doubt,  they  could  be  traced  to  an 
infection  through  milk  and  to  a  peculiar  new  eruptive 
disease  upon  the  teats  and  udders  of  cows.  From  the 
evidence  that  is  now  available,  one  is  justified  in  regard- 
ing it  as  established  that  the  outbreaks  of  scarlet  fever 
referred  to  had  no  relation  to  the  disease  of  cows, 
which  was  in  reality  only  a  somewhat  unusual  form  of 
cow  pox. 


116  MILK  HYGIENE 

Malet 33  cites  an  example  of  a  milk  epidemic  wherein 
from  August  21st  to  the  2d  of  September,  18  persons  be- 
longing to  11  households  were  attacked  with  scarlet 
fever  after  drinking  milk  from  a  farm  where  there  was 
a  scarlet  fever  patient. 

[The  cases  next  following  are  selected  from  among 
those  cited  by  Swithinbank  and  Newman.34 

Buffalo,  New  York  (reported  by  Wende).  "  Two 
outbreaks  of  scarlet  fever  occurring  in  1899  in  Buffalo 
were  traced  to  an  infected  milk  supply.  The  first  out- 
break was  that  of  57  children,  the  second  was  less  severe 
and  numbered  only  20  cases.  The  channel  of  infection 
was  well  traced  out  in  the  former,  and  it  was  found  that 
on  the  implicated  dairy  premises  there  were  two  cases 
of  desquamating  scarlet  fever.  One  was  a  child,  aged  9, 
the  other  a  young  man  aged  19  who  did  the  milking  and 
in  other  ways  assisted  in  the  dairy  during  his  illness. 
The  57  cases  were  almost  simultaneous  in  occurrence, 
and  the  severity  of  the  attack  appeared  to  depend  upon 
the  quantity  of  the  implicated  milk  consumed. " 

London,  1901.  The  total  number  of  cases  was  293,  all 
resulting  from  one  polluted  milk  source.  "  The  out- 
break occurred  on  the  delivery  course  of  a  certain  con- 
tractor in  London.  He  obtained  milk  from  38  farms. 
On  one  of  these  farms  there  were  four  cases  of  scarlet 
fever,  the  farmer,  his  wife,  son  and  daughter.  The  cows 
were  healthy. ' '  The  cases  were  widely  scattered  in  Lon- 
don but  were  all  directly  traceable  to  milk  from  the  im- 
plicated farm.  "  The  large  number  of  adults  attacked 
differentiated  this  outbreak  from  those  of  ordinary  type. 
After  the  regular  distribution  had  been  stopped  the  con- 

33  Reference  in  Recueil  de  med.  vetr.,  1895. 

34  Bacteriology  of  Milk.     For  original  references  to  cases  cited, 
see  this  work. 


ASIATIC  CHOLERA  117 

tractor  then  sent  his  milk  to  other  consumers,  who  then 
contracted  scarlet  fever." 

Beverly  and  Salem,  Massachusetts,  1901.  The  num- 
ber of  cases  was  60,  all  resulting  from  one  polluted 
source.  "  The  dairyman  in  this  outbreak  produced  5 
cans  of  milk  daily  and  obtained  14  other  cans  from  3 
neighbors.  On  one  of  these  3  farms,  3  children  had  been 
ill ;  a  girl  of  16  had  sore  throat,  another  girl  of  12  and  a 
boy  of  14  followed  a  few  days  later  with  a  similar  affec- 
tion, namely,  swelling  of  the  glands  in  the  neck,  and  gen- 
eral malaise.  One  of  them  had  a  slight  rash.  After  the 
recovery  from  acute  condition  they  assisted  in  handling 
the  milk.  The  outbreak  was  very  sudden,  and  promptly 
declined  from  a  time  dating  a  few  days  after  the  milk 
supply  from  the  farm  was  stopped.  The  fatality  was 
high,  as  many  as  11  deaths  occurring.  The  distribution 
of  the  cases  of  scarlet  fever  was  localized  to  the  distri- 
bution of  the  milk  in  question."  L.  P.] 

d.  Asiatic  cholera.  From  what  we  now  know  of  the 
epidemiology  of  cholera  it  cannot  be  doubted  that  the 
spread  of  the  germs  of  cholera  is  due  chiefly  to  drinking 
water ;  nevertheless  the  possibility  of  its  spread  through 
milk  and  other  foods  cannot  be  left  out  of  consideration. 
Examples  of  transmission  through  milk  are  certainly 
not  numerous ;  one  of  the  best  established  is  the  follow- 
ing reported  by  Simpson :  On  board  a  ship  in  the  harbor 
of  Calcutta,  10  persons  fell  victims  to  cholera  after 
drinking  milk  sold  by  a  native.  Four  patients  died,  5 
others  were  seriously  ill,  and  one  who  drank  but  little 
of  the  milk  was  slightly  affected.  It  was  learned  that 
the  milk  had  been  diluted  with  water  from  a  tank  into 
which  the  excrement  of  a  cholera  patient  had  been 
thrown  a  few  days  before.  Among  those  who  did  not 
drink  the  milk  there  was  no  illness. 

Simpson  was  able  also  to  trace  a  small  cholera  epi- 


118  MILK  HYGIENE 

demic  in  a  prison  in  Calcutta,  with  considerable  cer- 
tainty, to  the  distribution  of  the  cholera  bacilli  through 
the  milk,  and  it  was  probable  that  the  milk  was  already 
infected  before  delivery.  Graffky  also  reported  an  epi- 
demic caused  by  infection  through  milk. 

In  quite  fresh  milk,  cholera  bacilli  appear  to  succumb 
readily  to  its  bactericidal  action,  but  they  increase 
rapidly  in  older  milk  but  are  again  checked  and,  at  last, 
killed,  as  the  acidity  increases. 

e.  Tuberculosis.  Tubercle  bacilli  may  enter  milk  not 
only  from  tuberculous  cows  and  infected  stables  but  also, 
without  doubt,  from  tuberculous  people.  Of  course 
there  is  no  definite  illustration — for  obvious  reasons — of 
transmission  of  tuberculosis  in  this  way ;  but  if  one  con- 
siders what  a  quantity  of  tubercle  bacilli  may  be  ex- 
creted daily  by  a  consumptive,  the  possibility  of  such 
transmission  can  scarcely  be  disputed,  although  the  dan- 
ger is  considerably  lessened  by  the  fact  that  the  number 
of  tubercle  bacilli  will  not  increase  while  the  milk  is  kept. 
It  is  justifiable,  therefore,  to  forbid  tuberculous  people 
working  with  market  milk. 

/.  Other  diseases.  It  is  stated  in  text  books  that  there 
are  instances  of  the  transmission  of  syphilis,  and  there 
are  reports  in  English  journals  of  epidemics  of  sore 
throat  and  of  erysipelas  which  are  said  to  have  come 
from  infection  through  milk.  In  these  latter  cases,  how- 
ever, it  is  doubtful  if  the  infectious  material  came  di- 
rectly from  sick  people,  for  the  microbes  concerned 
(chiefly  streptococci)  may  gain  access  to  milk  from  other 
sources. 

[As  illustrations  of  such  outbreaks  of  sore  throat, 
the  three  following  cases  are  taken  from  among  those 
summarized  by  Swithinbank  and  Newman.35 

;!5  Bacteriology  of  Milk. 


SEPTIC  SORE  THROAT  119 

In  Anglesey,  in  1897,  15  people  who  took  milk  of  one 
dairy,  became  affected  at  about  the  same  time  with  sore 
throat.  Several  persons  in  the  affected  families  who 
consumed  milk  from  the  same  source  but  in  a  boiled  state 
escaped  the  sore  throat,  the  chief  evidence  of  which  was 
tonsilitis.  The  bacteriological  examination  of  the  milk 
revealed  the  presence  of  Streptococcus  pyogenes  and 
Staphylo coccus  pyogenes,  but  no  Bacterium  diphtheria. 
Bacteriological  examination  of  the  patients'  throats 
yielded  precisely  similar  results. 

"  In  May,  1902,  an  outbreak  occurred  in  Lincoln, 
affecting  a  large  number  of  persons.  Dr.  Brook  had 
seventy-five  cases  in  his  own  practice.  The  chief  symp- 
toms were  erythema  of  the  face,  and  sore  throat.  In 
many  cases  a  drab  colored  fur  covered  the  tonsils.  A 
roseolous,  papular  eruption,  in  some  cases  appearing  to 
be  urticarial,  occurred  in  two-thirds  of  the  cases.  There 
was  no  marked  fever,  except  in  cases  having  complica- 
tions. The  pulse  rate  was  not  increased,  and  no  albu- 
minuria  occurred.  The  onset  was  sudden,  and  in  no 
case  out  of  the  seventy-five  investigated  by  Dr.  Brook 
was  infection  communicated  to  others  by  contact. 
Nearly  all  of  the  patients  were  adults,  and  well  advanced 
in  years.  The  complication  most  commonly  met  with 
was  swelling  and  tenderness  of  the  cervical  glands. 
With  one  doubtful  exception,  all  the  patients  had  had 
milk  from  the  same  dairy.  Boiling  the  milk  appeared  to 
prevent  persons  from  taking  the  complaint.  The  poison 
seemed  to  be  present  particularly  in  the  cream.  The 
differences  between  the  disease  and  scarlet  fever  were 
very  marked. 

4 '  A  sudden  outbreak  of  a  severe  form  of '  septic  sore 
throat  '  occurred  at  Bedford  at  the  end  of  June,  1902. 
On  27th  June,  the  first  case  occurred;  on  29th  June,  4 
cases  occurred;  30th  June,  15  cases  occurred;  1st 


120  MILK  HYGIENE 

July,  13  cases ;  2nd  July,  3  cases ;  3rd  July,  2  cases ;  and 
4th  July  to  8th  July,  4  cases — making  a  total  of  42  cases 
in  22  families.  The  symptoms  included  redness,  swell- 
ing of  the  throat,  fauces,  palate,  and  uvula,  with  numer- 
ous spots,  patches  of  exudation,  and  in  some  cases 
ulcers.  The  general  symptoms  consisted  of  severe  head- 
aches, giddiness,  backache,  and  pains  in  the  limbs,  very 
much  like  an  attack  of  influenza.  The  temperature  was 
about  102°  to  103°  F.,  but  in  a  few  cases  was  higher.  In 
some  cases  there  was  gastric  and  intestinal  disturbance. 
Great  weakness  was  also  present.  In  every  case  the 
milk  supply  was  obtained  from  the  same  dairy.  On 
Sunday,  30th  June,  many  persons  consumed  cream  with 
fruit,  and  these  included  nearly  all  the  worst  cases.  In 
some  families  children  who  drank  boiled  milk  escaped, 
whilst  parents  who  consumed  unboiled  milk  or  cream 
were  attacked.  One  man  took  cream  in  the  form  of  ice- 
cream, and  had  a  severe  attack. ' ' 

It  must,  however,  be  regarded  as  possible  that  these 
cases  of  sore  throat  were  caused  not  by  contamination 
of  the  milk  from  a  human  source  but  to  the  presence  of 
organisms  of  suppuration  eliminated  by  cows  with  dis- 
eased udders.  L.  P.] 

The  transmission  of  measles,  small-pox,  pest,  dysen- 
tery, or  cerebro-spinal  meningitis  by  milk  has  not  been 
observed,  but  the  possibility  of  such  transmission  can 
scarcely  be  doubted. 

VI.    CONTAMINATION  WITH   OTHER    BACTERIA 

Milk  becomes  infected  with  bacteria  during  the  act  of 
milking.  These  contaminating  organisms  come  partly 
from  the  teat  canal,  partly  from  dirt,  hairs,  and  dandruff 
on  the  skin  of  the  cow,  partly  from  the  hands  and  cloth- 
ing of  the  milkers,  partly  from  the  dust  of  the  stable. 
Still  more  are  added  when  the  milk  is  collected  and 


CONTAMINATION  WITH  BACTERIA        121 

stored  in  unsterilized  vessels  or  when  it  is  exposed  to 
the  air.  It  is  evident  that  the  number  of  bacteria  found 
in  freshly  drawn  milk  varies  greatly  according  to  the 
conditions  of  cleanliness  of  the  stable  and  the  cows,  and 
as  to  the  cleanliness  and  carefulness  observed  during 
milking. 

Freshly  drawn  milk  possesses  a  certain  bactericidal 
action  which,  however,  does  not  seem  to  affect  all  forms 
of  bacteria.  The  number  of  living  bacteria  in  milk  may 
be  lessened  appreciably  in  the  course  of  a  few  hours  as 
a  result  of  this  activity,  but  the  action  does  not  last  and, 
under  appropriate  temperature  conditions,  bacteria 
soon  begin  to  increase  and  their  number,  at  times,  be- 
comes enormous.  The  rapidity  with  which  the  bacteria 
increase  after  milking  is  dependent  entirely  upon  the 
temperature  at  which  the  milk  is  kept. 

If  the  milk  is  cooled  immediately  after  being  drawn 
and  is  kept  at  a  temperature  not  higher  than  10°  C. 
(50°  F.)  there  is  no  material  increase  of  bacteria  during 
the  first  24  to  36  hours;  even  at  14°  to  15°  C.  (57.2°  to 
59°  F.)  the  increase  is  relatively  slight.  But  as  the 
temperature  rises,  the  number  of  bacteria  increases 
rapidly  and  bacteria  are  very  numerous  in  milk  that 
has  stood  at  20°  to  25°  C.  (68°  to  77°  F.)  for  12  hours. 

In  order  to  illustrate  the  importance  of  cleanliness 
in  the  stable  and  during  milking,  the  following  figures 
determined  by  Grotenfeld  may  be  of  use.  In  one  c.c.  of 
milk  from  cows  particularly  well  cared  for,  he  found  106 
bacteria,  while  the  freshly  drawn  milk  of  cows  in  a  dirty 
stable  contained  617,000  bacteria  per  c.c.  Therefore,  one 
cannot  generalize  as  to  the  number  of  bacteria  in  freshly 
drawn  milk,  but  milk  from  well-cared-for  and  carefully 
milked  cows  will,  as  a  rule,  contain  hardly  more  than 
1000  to  6000  bacteria  per  c.c.  The  following  results  show 
the  potent  effect  of  cold  in  checking  the  increase  of  bac- 


122 


MILK  HYGIENE 


teria.    The  milk  used  contained  about  9300  bacteria  in 
one  c.c.  and  was  kept  at  15°,  25°,  and  35°  C. : 


ATl5°C.  (59°F.) 

AT25°C.  (77°  F.) 

AT35°C.  (95°  F.) 

Beginning  of  the  test. 

9,300 

9,300 

9,300 

After    3  hours 

10,000 

18,000 

30,000 

After    6  hours 

25,000 

172,000 

12,000,000 

After    9  hours 

46,000 

1,000,000 

35,280,000 

After  24  hours 

5,700,000 

50,000,000 

577;500,000 

At  the  low  temperature,  it  is  seen  that  the  increase 
is  at  first  very  slight.  Moore  found  that  the  number  of 
bacteria  in  milk  kept  at  21°  C.  (70°  F.)  did  not  increase 
during  the  first  6  to  9  hours  but  then  increased  rapidly ; 
he  also  found  that  in  the  course  of  from  36  to  48  hours, 
no  appreciable  increase  in  the  number  took  place,  if 
the  temperature  did  not  rise  above  12°  to  13°  C.  (53.6° 
to  55.4°  F.)  and  that  a  still  lower  temperature,  as  4°  to 
5°  C.  (39.2°  to  41°  F.),  could  prevent  the  increase  of 
bacteria  for  a  longer  period.  Meyer  found,  through 
experiments  carried  on  in  Jensen's  laboratory,  that 
cooling  the  milk  to  10°  to  12°  C.  (50°  to  53.6°  F.)  checks 
the  growth  of  bacteria  for  a  long  time. 

It  is  evident,  from  all  of  this,  that  the  quick  and  per- 
manent cooling  of  the  milk  to  10°  to  12°  C.  (50°  to  53.6° 
F.)  is  most  important  in  preserving  it. 

Of  course  the  number  of  bacteria  in  market  milk 
varies  greatly  according  to  its  age  and  care  and  to  the 
temperature  of  the  air.  Experience  gained  in  most  of 
the  larger  cities  shows  the  bacterial  content  of  market 
milk  to  be  seldom  below  50,000  to  100,000  per  c.c.  but  it  is 
often  greater,  varying  between  1,000,000  to  30,000,000; 
indeed,  not  infrequently,  even  from  100,000,000  to  150,- 
000,000  have  been  found.  And  such  milk  may  not  be 
noticeably  tainted. 


SPONTANEOUS  CHANGES  IN  MILK        123 

If  the  question  be  asked :  What  is  the  sanitary  signifi- 
cance of  the  existence  of  this  mass  of  bacteria  ?  we  must 
consider  the  changes  which  bacteria  in  pure  culture  may 
cause  in  milk,  and  which  were  mentioned  above,  for  it 
is  evident  that  these  same  changes  occur,  although  often 
very  much  less  clearly  marked,  in  market  milk  rich  in 
bacteria.  When  milk  is  kept  a  long  time  it  may  become 
altered  in  one  of  several  ways,  of  which  the  following 
are  the  most  common : 

1.  The  well  known  coagulation  (curdling),  following 
the  formation  of  acid,  is  the  most  frequent. 

2.  Less  often,  a  more  or  less  disagreeable  (putrid) 
odor  and  taste  occur  without  much  acid  formation  and 
without  coagulation. 

3.  Still  less  frequently,  the  milk  becomes  slimy  or 
i  i  stringy, ' '   either  without   souring,   or   accompanying 
the  process  of  souring. 

Sour  milk.  It  is  known  that  sour  milk  has  no  harmful 
effect  on  healthy  people.  But  it  is  different  with  those 
suffering  with  catarrh  of  the  stomach,  and  with  small 
children.  In  these  cases  a  degree  of  acidity  not  be- 
trayed by  coagulation  or  appreciable  sour  taste  appar- 
ently may  cause  vomiting  and  indigestion,  possibly  be- 
cause the  numerous  lactic  acid  bacteria  rapidly  increase 
with  the  warming  of  the  milk  in  the  stomach,  and  cause 
coagulation  before  the  gastric  juice  can  check  their 
growth.  Milk  in  which  the  lactic  acid  fermentation  is  so 
far  advanced  that  it  will  not  stand  boiling,  or  the  taste 
of  which  is  slightly  sour,  must  therefore  be  regarded  as 
unfit  for  food  for  small  children.  The  number  of  bac- 
teria in  milk  does  not  give  us  a  safe  criterion  for  judging 
it  in  this  connection,  but  the  degree  of  acidity  furnishes 
a  reliable  guide.  (See  below.) 

Putrid  milk.  Even  though  the  taste  is  not  yet  decid- 
edly foul,  but  is  only  bitter  (formation  of  peptone) 


124  MILK  HYGIENE 

nausea  and  vomiting  may  be  caused,  even  in  adults,  and 
there  are  many  instances  of  the  poisoning  of  large  num- 
bers of  people  by  such  milk.  This  alteration  is  most  fre- 
quently observed  in  summer  when  the  milk  is  not  prop- 
erly cooled,  and  occurs  especially  in  milk  that  has  been 
warmed  or  even  boiled  for  a  short  time  [pasteurized], 
without  sufficient  cooling  afterward. 

Slimy  milk.  According  to  information  at  hand,  the 
slimy  change  seems  to  have  no  harmful  effect,  although 
it  may  make  the  milk  most  unappetizing.  In  Sweden, 
however,  this  change  is  produced  and  "  langmjolk  "  is 
prepared  for  food,  as  sour  milk  (curds  and  whey)  is 
prepared  in  other  countries.  Milk  that  is  inclined  to  the 
slimy  change  should  not,  at  any  rate,  be  fed  to  small 
children. 

Some  bacteria  that  occur  in  milk  but  which,  on  ac- 
count of  their  properties  or  small  number,  do  not  have 
any  noticeable  effect  upon  the  appearance  or  changes 
of  the  milk,  may  still  be  harmful.  These  are  sporulat- 
ing  forms,  as  the  hay  bacilli  or  members  of  the  group  of 
butyric  acid  bacilli,  which  may  break  up  the  casein  with 
the  formation  of  albumoses,  peptones  and  amid-  and  am- 
monia compounds.  Sometimes  there  are  bacteria  which 
generate  special  poisons  that  go  into  solution  in  the  milk 
or  that  remain  attached  to  the  bacteria  cells.  Little  is 
known  of  these  forms,  although  the  opinion  has  been 
frequently  expressed  that  these  very  bacteria  play  an 
important  part  in  the  etiology  of  diarrhoea  in  children. 
Finally,  there  may  be  bacteria  which  are  pathogenic  for 
animals  and  for  man  and  that  are  capable  of  causing 
inflammation.  Such  bacteria  are  very  common  in  mar- 
ket milk.  In  the  examination  of  56  samples  of  market 
milk  in  Berlin,  Beck  found  streptococci  in  34,  which 
caused  fatal  enteritis  when  fed  to  rabbits  and  guinea 
pigs.  In  injecting  milk  in  the  abdominal  cavity  of  rab- 


SPONTANEOUS    CHANGES    IN    MILK     125 

bits  (in  order  to  test  it  for  tubercle  bacilli)  Friis  discov- 
ered that  15  of  the  28  samples  contained  bacteria  which 
caused  either  peritonitis  or  abscesses  or  pyaemia. 
Guinea  pigs  were  generally  useless  for  his  experiments 
because  they  all  died  of  peritonitis.  Similar  results  have 
been  obtained  by  many  others. 

The  forms  of  bacteria  considered  in  this  connection 
are  chiefly  streptococci,  staphylococci  and  members  of 
the  colon  group,  some  of  which  are  generally  present, 
although,  perhaps,  in  quite  small  amounts,  in  market 
milk;  besides  these,  there  are  still  many  other  kinds, 
some  of  them  occurring  regularly,  in  small  numbers,  and 
some  are  only  met  with  now  and  then.  Where  do  these 
bacteria  come  from?  Primarily  from  the  dirt  that  gets 
into  the  milk  when  it  is  drawn, — it  is  a  well-known  fact 
that  the  excrement  contains  numerous,  and  sometimes 
pathogenic,  bacteria.  They  may  also  come  from  cases 
of  mastitis  and  metritis  in  the  stable ;  moreover  these 
forms  of  bacteria  are  widespread  and  probably  they 
very  often  occur  in  cow  stables,  as  is  shown  by  the  fre- 
quent occurrence  of  calf  cholera.  ."  Calf  cholera  "  is  a 
common  name  for  a  group  of  fatal  diseases  of  new-born 
calves  among  which  the  most  usual  forms  are  navel 
infection  (most  frequently  caused  by  .streptococci,  colon 
bacilli  and  pseudo-colon  bacilli)  and  diarrhoea  or  dysen- 
tery of  calves  (in  most  cases  caused  by  colon  bacilli). 

It  does  not  follow  that  all  milk  containing  strepto- 
cocci or  the  other  bacteria  referred  to  above  is  harmful 
or  dangerous.  But  if  these  are  present  in  large  num- 
bers, they  make  the  milk  suspicious  and  there  are  many 
evidences  that  such  milk  has  been  most  injurious.  It  is 
highly  probable  that  a  very  great  part  of  the  gastro- 
enteritis, so  harmful  to  small  children,  is  traceable  di- 
rectly to  these  bacteria.  The  fact  that  the  mortality 
among  small  children  in  general  has  decreased  to  a  great 


126  MILK  HYGIENE 

extent  where  the  milk  is  bacteriologically  clean  or  has 
been  sterilized  according  to  Soxhlet's  method,  is  one 
of  the  arguments  in  favor  of  this  view.  Heubner  is  of 
the  opinion  that  infant  mortality  has  been  diminished  in 
this  way  to  the  extent  of  27  per  cent. 

In  order  to  prevent  too  great  contamination  by  such 
bacteria — it  is  difficult  to  wholly  exclude  them — there  is 
no  other  way  than  strictly  to  guard  the  health  of  the 
herds,  as  well  as  the  cleanliness  of  the  stable  [of  the 
utensils  and  receptacles]  and  of  the  attendants.  The 
eventual  danger  may  be  partly  removed  by  pasteurizing 
or  boiling  the  milk. 

VII.    ADMIXTURE  OF  DIRT 

As  has  already  been  stated,  it  is  customary  for  milk 
to  become  more  or  less  contaminated  with  particles  of 
dirt  and  their  adherent  bacteria  during  milking.  The 
dirt  consists,  principally,  of  bits  of  manure  and,  besides 
this,  hairs,  dandruff,  particles  of  food,  earth  and  dust. 

Usually,  after  milking  each  cow,  the  milk  is  passed 
through  a  strainer  which  retains  particles  of  dirt ;  but  if 
the  strainer  is  not  cleaned  very  frequently,  the  particles 
of  dung  and  dirt  are  softened  in  the  milk,  bacteria  are 
washed  through  and  substances  that  carry  abnormal 
odors  and  tastes  are  set  free  in  the  milk.  By  straining, 
then,  one  accomplishes  only  the  removal  of  the  larger 
and  more  solid  particles  of  dirt  that  are  quite  harmless 
in  themselves,  such  as  hairs,  cellulose,  sand,  etc. 

When  unclean  milk  is  permitted  to  stand,  a  distinct 
sediment  is  formed  and  its  presence  signifies  lack  of 
cleanliness  in  respect  to  production. 

The  importance  of  dirt  contamination  is  due  chiefly 
to  the  addition  of  bacteria  with  the  dirt  and  to  the  solu- 
tion of  faecal  matter ;  the  visible  dirt  is  important  only 
as  it  makes  the  milk  unappetizing.  It  follows  that  a 


ADMIXTURE  OF  DIRT  127 

greater  or  less  dirt  content  has  a  great  influence  upon 
the  healthful-ness  and  keeping  quality  of  the  milk;  this 
is  emphasized  by  a  study  of  the  bacterial  content  of  cow 
dung.  Wiithrich  and  Freudenreich  found  this  to  vary 
according  to  the  kind  of  feed ;  the  bacteria  in  the  dung 
of  cows  fed  with  hay  appeared  to  be  most  numerous; 
1  gramme  of  such  excrement  contained  375,000,000 
bacteria. 

Of  course  the  quantity  of  dirt  in  market  milk  differs 
very  greatly.  An  investigation  in  Hamburg  showed  that 
the  quantity  varied  from  0.0  to  183.5  milligrams  per 
liter ;  on  the  average,  there  were  13.5  milligrams  of  dry 
dirt  in  a  liter  of  milk.  In  other  experiments,  Schmelk  in 
Christiania  found  an  average  of  11  milligrams  in  a  liter, 
von  Hellens  (Helsingfors)  found  only  1.79;  in  Berlin, 
Renk  showed  the  average  to  be  10.3;  in  Halle,  14.92; 
in  Leipsig,  3.8  and  in  Munich,  9.0.  The  maximum  quan- 
tity in  each  case  was  much  greater  than  the  averages 
mentioned,  although  it  never  reached  the  maximum  for 
Hamburg  milk. 

In  Dresden  the  standard  regarding  market  milk 
states  that  it  must  not  contain  more  than  8  milligrams  of 
dirt  per  liter. 

In  Denmark  there  are  no  general  regulations  con- 
cerning the  dirt  content  of  milk ; 36  there,  too,  it  varies 
considerably,  it  is  great  in  the  milk  from  distillery  fed 
herds  and  less  in  milk  delivered  by  the  large  companies. 

36  In  1895,  the  Copenhagen  health  commission  had  39  samples  of 
milk  tested  for  dirt,  which  was  found  in  small  quantity,  varying  be- 
tween 1  and  13  milligrams  per  liter. 


PART    IV. 


PASTEURIZATION    AND    STERILIZATION 


IN  the  household,  milk  is  boiled  to  make  it  keep 
longer  and  this  process  serves  also  to  kill  any  pathogenic 
bacteria  that  may  be  present.  Little  by  little,  the  public 
has  learned  that  milk  often  contains  disease  producing 
germs  and  that  small  children  are  especially  exposed  to 
their  harmful  effects,  so  the  custom  has  become  more  or 
less  general  of  sterilizing  milk  intended  for  infants, 
Quite  naturally,  the  idea  developed  to  sterilize  market 
milk,  by  heating  before  it  was  offered  for  sale.  By 
this  means,  the  following  desired  results  have  been  ob- 
tained: the  milk  keeps  for  a  longer  time,  it  loses  its 
capacity  for  infection,  and  the  annoying  process  of  ster- 
ilization in  the  home  is  avoided.  In  most  large  cities 
there  are  one  or  more  companies  engaged  in  the  sale  of 
sterilized  or  pasteurized  milk. 

The  difference  between  pasteurization  and  steriliza- 
tion consists,  essentially,  in  the  greater  degree  of  heat 
applied  during  the  latter  process. 

I.    PASTEURIZATION 

By  pasteurizing  a  fluid  is  generally  understood  heat- 
ing it  to  a  certain  temperature  which  is  sufficient  to  in- 
crease its  keeping  qualities.  It  is  sometimes  used  to 
indicate  heating  to  50°  to  60°  C.  (122°  to  140°  F.)  and 
sometimes  to  the  use  of  a  higher  temperature.  In  ref- 
erence to  milk  and  dairy  products,  the  term  "  pasteur- 
ization "  is  used  in  a  more  definite  sense.  In  butter- 

128 


129 

making  pasteurization  is  understood  to  mean  a  brief 
heating  of  the  cream  and  whole  milk  to  80°  to  85°  C. 
(176°  to  185°  F.),  the  purpose  of  which  is  to  kill  most 
of  the  existing  bacteria,  in  order  to  prevent  those  fer- 
mentations of  the  cream  which  might  cause  the  butter  to 
be  of  inferior  quality.  At  the  same  time,  pathogenic 
micro-organisms  (particularly  tubercle  bacilli)  are  made 
harmless.  In  some  places, ' i  pasteurized  butter ' '  is  made 
solely  for  the  latter  purpose. 

In  Denmark,  on  account  of  the  danger  of  spreading 
tuberculosis  among  animals,  it  is  provided  by  law  that 
skim  milk  and  buttermilk  delivered  from  creameries  to 
be  used  as  food  for  animals  must  have  been  heated  to  85° 
C.  (185°  F.).  In  this  connection,  however,  the  law  does 
not  mention  pasteurization  but,  in  practice,  pasteurized 
separator  milk  (or  buttermilk)  is  understood  to  be  milk 
that  has  been  subjected  approximately  to  the  above  men- 
tioned temperature  and  that  does  not  react  to  Storch's 
or  to  the  guaiac  tests. 

Since  market  milk  is  pasteurized  especially  in  order 
to  render  harmless  any  disease  producing  germs  that 
may  possibly  be  present,  and  since  the  majority  of  con- 
sumers are,  doubtless,  of  the  opinion  that  pasteurized 
milk  may  be  used  with  perfect  safety  without  further 
heating,  it  should  be  strictly  required  that  market  milk 
sold  as  "  pasteurized  "  shall  have  been  subjected  to  a 
sufficient  degree  of  heat  to  kill  with  certainty  all  of  the 
pathogenic  micro-organisms  that  are  present. 

The  pathogenic  bacteria  that  are  of  importance  in 
this  connection  are  the  germs  of  tuberculosis,  typhoid 
fever,  diphtheria,  cholera  and  pest  and  pyogenic  cocci 
and  the  virus  of  foot-and-mouth  disease.  These  have 
been  shown  by  recent  investigations  to  be  killed  by  mo- 
mentary heating  to  70°  to  80°  C.  (158°  to  176°  F.)  and 
they  die  at  a  temperature  of  65°  C.  (150°  F.),  if  this 
9 


130  MILK  HYGIENE 

degree  of  heat  is  maintained  long  enough.  This  is  also 
true  of  many  bacteria  occurring  in  milk  which  may  be 
injurious,  yet  which  cause  no  specific  disease.  There- 
fore, milk  may  be  pasteurized  either  by  a  brief  heating 
at  a  higher  temperature  or  a  longer  heating  at  a  lower 
temperature.  But  the  spores  of  bacteria  and  the  thermo- 
philic  forms  that  are  specially  capable  of  resisting  heat, 
are  not  destroyed  by  these  methods,  so  pasteurization 
does  not  have  the  same  effect  as  sterilization.  Milk  may 
be  pasteurized  in  different  ways.  The  following  three 
methods  are  those  most  commonly  used : 

2.  The  milk  is  heated  during  one-quarter  to  one  hour 
at  from  80°  to  85°  (176°  to  185°  P.)  while  it  is  flowing 
through  an  appropriate  pasteurizing  apparatus ;  then  it 
is  cooled  immediately. 

2.  The  milk  is  heated  from  one  quarter  to  one  hour 
at  about  65°  C.  (150°  F.)  in  a  tank  or  vat.     The  milk 
flows  directly  from  this  vessel  into  the  one  in  which  it 
is  to  be  sold,  or  it  is  first  passed  through  a  cooler. 

3.  The  milk  is  poured  into  well  cleansed  or  sterilized 
bottles  or  metal  vessels,  is  then  heated  for  a  consid- 
erable time  at  65°  to  80°  C.  (150°  to  176°  F.),  then  the 
bottles  or  vessels  are  sealed  and  quickly  cooled. 

For  sanitary  reasons  the  last  of  these  methods  is 
unquestionably  to  be  preferred,  but  it  has  not  been 
adopted  extensively  on  account  of  its  cost.  Heating 
many  small  vessels  requires  a  great  amount  of  heat  and 
causes  great  loss  in  bottles,  if  such  are  used.  The  initial 
cost,  also,  and  the  amount  of  labor  required  are  con- 
siderable. 

If  one  of  the  first  two  methods  is  employed,  the  pas- 
teurized milk  must  be  drawn  into  vessels  (bottles  or 
metal  cans)  which  have  previously  been  properly 
sterilized. 

Pasteurizing  milk  and  then  placing  it  in  unsterilized 


PASTEURIZATION  131 

vessels  has  no  effect.  Indeed,  if  bottles  are  used,  this  is 
to  be  forbidden  as  injurious  to  health.  Very  often  the 
milk  is  drunk  directly  from  the  bottle,  which  may  be 
infected  by  this  means  and,  in  spite  of  washing,  fresh 
milk  may  be  infected  as  it  is  poured  out.  In  this  connec- 
tion, what  is  to  be  understood  by  sterilization  ?  The  aim 
is,  so  far  as  possible,  to  kill  all  microbes.  The  task  is 
not  difficult  with  metal  vessels  because,  after  thorough 
mechanical  cleansing,  these  can  be  subjected  to  very  hot 
steam  or  can  be  scalded.  With  glass  bottles,  the  task  is 
more  difficult,  because  strong  heat  causes  much  break- 
age, and  if  the  price  of  the  milk  is  not  such  as  to  cover 
this  loss,  another  method  must  be  used.  Thorough  me- 
chanical cleansing,  scouring  the  outside  as  well  as  the 
inside,  followed  by  long  soaking,  in  a  strong,  warm  solu- 
tion of  washing  soda  at  70°  C.  (158°  F.)  and  rinsing  in 
pure,  lukewarm  water,  is  believed  to  kill  with  reasonable 
certainty  all  pathogenic  forms  and  also  the  majority  of 
other  milk  bacteria. 

A  very  large  number  of  machines  for  the  quick  pas- 
teurization of  milk  have  been  built,  chiefly  for  use  in 
creameries.  The  principle  of  these  machines  is  dif- 
ferent. One  of  the  first  pasteurizers  was  that  made  by 
Fjord;  it  consists,  as  the  diagrams  (Figs.  5  and  6,  pp. 
132  and  133)  show,  of  a  tinned  copper  tank  provided  with 
an  insulated  steam  jacket.  The  tank  contains  rotating 
arms  by  which  the  milk  is  thrown  against  the  heated 
walls.  The  milk  is  admitted  at  the  bottom  through  pipe 
H  and  leaves  the  apparatus  at  the  top. 

By  regulating  the  quantity  of  milk  admitted,  the 
rapidity  of  the  revolving  arms  and  the  amount  of  steam, 
the  milk  may  be  heated  as  desired.  Many  other  pasteur- 
izing machines  are  built  according  to  the  same  principle. 

In  other  pasteurizers,  the  milk  is  heated  while  it 
flows  in  thin  layers  over  heated  metal  surfaces,  or  while 


132 


MILK  HYGIENE 


forced  between  two  surfaces  lying  close  to  each  other, 
or  while  it  is  being  passed  through  a  system  of  heated 
pipes.  In  some  pasteurizers  hot  water  serves  as  the 
source  of  heat  for  the  metal  surfaces  or  pipes,  while 
steam  is  used  in  others. 


FIG.  5. 


Fjord's  pasteurizing  apparatus. 

Since  one  can  hardly  be  sure  that  every  particle  of 
the  whole  volume  of  milk  is  heated  to  a  given  tempera- 
ture by  this  method  of  pasteurization,  it  should  be  re- 
quired that  the  temperature  of  the  milk,  when  it  leaves 
the  apparatus,  shall  be  at  least  80°  C.  (176°  F.).  If  this 


PASTEURIZATION 


133 


is  not  done,  it  cannot  be  regarded  as  certain  that  the 
milk  has  been  freed  from  pathogenic  micro-organisms. 
Moreover,  a  pasteurizer  which  is  to  prepare  milk  for 
use  as  food  must  fulfil  the  following  requirements : 

1.  The  entire  quantity  of  milk,  including  the  froth 
formed  during  heating,  must  be  heated  equally  to  the 
desired  temperature. 


FIG.  6. 


Fjord's  pasteurizing  apparatus. 


2.  The  apparatus  must  ivork  reliably,  in  order  that 
there  shall  be  no  danger  that  at  times  the  milk  is  not 
sufficiently  heated. 

3.  The  machine  must  be  easy  to  clean. 


134 


MILK  HYGIENE 


All  pasteurizing  apparatus  must  be  under  the  con- 
stant inspection  of  a  reliable  man,  or  must  be  provided 
with  a  self  regulator.  A  regulator  which  shuts  off  the 
milk  automatically  if  the  temperature  of  the  contents 
of  the  machine  falls  below  the  given  standard,  was  de- 
vised by  Henriques  and  Stribolt.  Up  to  the  present 
time,  this  principle  is  not  widely  applied,  but  doubtless 
it  deserves  to  be  introduced  into  the  better  plants  which 
prepare  and  sell  pasteurized  milk.  Fig.  6  shows  a 
Fjord  pasteurizer  with  a  self  regulator;  the  latter  con- 
sists of  a  metal  thermometer  (see  Fig.  7)  whose  free 
arm  (n)  is  attached  to  a  horizontal  rod  (r  y)  which  may 
move  a  valve  placed  in  the  entrance  pipe  to  the  pasteur- 
izer. 

FIG.  7. 


Automatic  temperature-regulator,  as  devised  by  Henriques  and  Stribolt. 

The  construction  is  shown  by  Fig.  7.  As  the  temperature  of  the 
milk  in  the  machine  rises,  the  two  arms  of  the  thermometer  approach 
each  other  and  the  valve  m  d  c  is  thus  pressed  back  by  the  horizontal 
rod  r  u,  which  presses  against  m  so  that  the  opening  at  b  k  is  free 


PASTEURIZATION 


135 


and  the  milk  can  pass  from  o  to  p.  If  the  temperature  falls,  the 
pressure  of  the  horizontal  rod  is  withdrawn  from  the  valve,  which  is 
then  caused  to  close  the  opening  by  means  of  a  spring,  s,  so  that  the 
milk  cannot  flow  to  the  pasteurizer;  thereupon  the  discharge  of  milk 
immediately  ceases,  and  not  until  the  milk  has  been  sufficiently 
heated  will  the  valve  open  again,  so  that  fresh  milk  may  enter  and 
expel  that  already  heated  from  the  apparatus. 


FIG.  8. 


m 

Schmidt's  milk-cooler;  a,  entrance  for  cold  water;  6,  exit  for  cold  water. 

From  the  pasteurizer,  the  milk  must  be  passed  over 
or  through  a  cooler  in  order  to  lower  the  temperature  as 
much  as  possible,  for  otherwise  it  would  soon  spoil. 

From  the  cooler,  the  milk  should  be  drawn  directly 
into  the  container  from  which  it  is  to  be  sold.  Fig.  8 
represents  a  cooler  which  consists  of  a  spirally  fluted 


136  MILK  HYGIENE 

metal  tank,  through  which  cold  water  or,  better,  ice 
water  is  passed  and  over  the  surface  of  which  milk 
slowly  flows. 

For  pasteurizing  milk  in  bottles  or  in  cans  an  appa- 
ratus of  different  construction  is  used.  Some  consist 
simply  of  a  water  bath;  a  large  shallow  metal  tank  is 
partly  filled  with  water  and  the  bottles  are  so  placed  in 
this  that  they  are  submerged  as  close  as  possible  to  the 
neck,  then  the  tank  is  closed  by  a  cover  and  the  water  is 
heated  with  steam. 

Other  pasteurizers  are  built  according  to  the  follow- 
ing principle:  there  is  a  perforated  drawer  in  a  large 
metal  tank  upon  which  the  filled  bottles  are  placed  close 
together  (Fig.  9) ;  after  the  tank  has  been  tightly  closed 
by  means  of  a  cover  or  door,  steam  is  admitted  until  the 
desired  temperature  is  reached.  Of  course  these  ma- 
chines are  also  adapted  to  sterilizing  at  a  higher  tem- 
perature (100°  to  110°  C.,  212°  to  230°  F.).  After 
from  one-half  to  one  hour's  heating,  the  bottles  are 
allowed  to  cool  a  little  before  the  tank  is  opened,  then 
they  are  immediately  sealed.  In  some  machines,  all  of 
the  bottles  are  sealed  before  the  tank  is  opened,  by 
means  of  a  specially  arranged  mechanism.  The  further 
cooling  of  the  bottles  is  attended  with  certain  difficulties, 
as  they  crack  easily.  This  may  be  accomplished  by 
passing  the  bottles  through  several  tanks  of  water  of 
progressively  lower  temperature,  or  by  slowly  lowering 
the  temperature  of  the  water  surrounding  them. 

While  the  fact  of  the  previous  heating  of  milk  to  not 
less  than  80°  C.  (176°  F.)  may  be  established  with  cer- 
tainty by  the  Storch  or  guaiac  tests,  it  is  not  possible  to 
determine  whether  or  not  the  milk  has  been  subjected  to 
a  less  degree  of  heat ;  moreover,  since  a  brief  heating  at 
80°  C.  (176°  F.)  is  cheaper  and  far  more  convenient  than 
a  longer  heating  at,  for  instance,  65°  C.  (150°  F.),  there 


PASTEURIZATION 


137 


is  much  to  be  said  in  favor  of  the  establishment  of  a  fixed 
rule  that  all  milk  designated  as  pasteurized  shall  be 
heated  to  at  least  80°  C.  (176°  F.),  that  is,  a  temperature 
that  can  be  determined  by  the  Storch  or  guaiac  test.  But 
there  is  another  side  to  the  question.  In  the  medical 


FIG.  9. 


Flaack's  apparatus  for  sterilizing  bottled  milk. 

world  the  sentiment  against  pasteurizing  at  high  tem- 
peratures has  been  growing  during  recent  years,  for  it 
has  been  claimed  that  this  causes  a  change  in  the  pro- 
teids  which  makes  them  less  digestible.  In  many  places, 
therefore,  the  longer  heating  at  a  lower  temperature,  has 


138  MILK  HYGIENE 

been  adopted.     All  milk  from  Bolles'  great  establish- 
ment in  Berlin,  is  handled  in  this  way. 

Under  these  conditions,  such  a  requirement  as  that 
mentioned  above  could  scarcely  be  maintained  but,  with- 
out doubt,  regulations  with  regard  to  the  sale  of  pas- 
teurized milk  should  be  laid  down,  and  the  following 
appear  to  be  appropriate : 

1.  Milk  sold  as  "  pasteurized  "  without  a  more  ex- 
plicit statement  must  have  been  heated  to  at  least  80°  C. 
(176°  F.). 

2.  Milk  that  has  been  pasteurized  by  heating  at  a 
lower  temperature,  shall  be  sold  as  "  pasteurized  "  only 
if  it  is  marked  with  a  label  giving  the  degree  of  heat  ap- 
plied, and  not  until  after  the  health  authorities  are  con- 
vinced that  the  establishment  in  question  is  prepared  to 
pasteurize  in  an  approved  and  effective  way. 

The  advantages  derived  from  pasteurizing  market 
milk,  from  a  hygienic  standpoint,  are  as  follows : 

1.  The  specific  pathogenic  bacteria  are  destroyed. 

2.  Most  of  the  other  bacteria  are  likewise  killed  and, 
therefore,  the  milk  keeps  better. 

3.  Pasteurization  necessitates  a  better  method  of  de- 
livering milk  than  that  commonly  employed  in  many 
places. 

By  means  of  pasteurization,  as  has  been  said,  the 
pathogenic  bacteria  and  the  larger  part  of  the  other 
bacteria  are  killed.  •  Since  the  bacterial  content  of  ordi- 
nary milk  is  most  variable,  and  since  the  forms  are  by 
no  means  always  alike,  the  number  of  bacteria  that  live 
through  pasteurization — even  after  heating  to  the  same 
temperature — is  not  even  approximately  the  same.  In 
other  words,  the  average  bacterial  content  of  milk  that 
has  been  pasteurized  a  short  time  cannot  be  stated. 
There  are  usually  only  very  few  bacteria  per  c.c.  in  pas- 
teurized milk  that  was  freshly  drawn  and  handled  in  a 


PASTEURIZATION  139 

cleanly  way;  while  under  other  conditions  hundreds, 
even  thousands  of  bacteria  are  to  be  found  in  every  c.c. 
of  pasteurized  milk.  Lactic  acid  forming  bacteria  in 
milk  are  killed  by  pasteurizing,  while  certain  harmless 
bacteria,  many  bacteria  of  putrefaction  and  spore  form- 
ing bacilli  survive ;  for  this  reason  pasteurised  milk  sel- 
dom sours  but  gradually  putrefies. 

No  absolute  conclusions  can  be  drawn  concerning  the 
effectiveness  of  pasteurization  from  the  bacterial  con- 
tent of  pasteurized  milk  sold  in  the  retail  market,  for 
one  does  not  know  the  nature  of  the  milk  before  pas- 
teurization, the  length  of  time  the  milk  has  been  kept 
since  pasteurization  or  the  temperature  at  which  it  has 
been  kept,  and  these  factors  are  largely  responsible  for 
an  abundance  of  bacteria. 

The  objections  to  pasteurization  are: 

1.  Even  by  the  use  of  a  self-regulating  pasteurizer,  it 
is  difficult  to  provide  absolute  guarantee  that  all  milk 
has  been  heated  to  the  required  temperature. 

2.  Pasteurization  incurs  expense,  therefore  the  milk 
costs  more. 

3.  To  a  certain  degree,  pasteurization  may  conceal  a 
tainted  condition  which  exists  before  heating.    Quite  an 
abundance  of  bacteria  of  putrefaction  and  other  bacteria 
may  be  present,  or  the  lactic  acid  fermentation  may  have 
begun  to  take  place;  these  bacteria  are  killed  by  pas- 
teurization, consequently  the  fermentations  and  changes 
that  were  under  way  are  interrupted.    Under  such  cir- 
cumstances, one  cannot  tell  by  the  appearance  or  taste 
of  milk  that  it  is  damaged  and  that  it  contains   the 
products  of  decomposition  of  the  albumen,  or,  possibly, 
even  toxic  substances.    On  the  whole,  there  is  no  way, 
at  the  present  time,  of  determining  whether  or  not  pas- 
teurized milk  was  damaged  before  it  was  heated,  while, 
with  respect  to  raw  milk,  the  keeping  quality  and  bac- 


140 


MILK  HYGIENE 


terial  content  furnish  sufficient  evidence  regarding  its 
true  condition. 

4.  The  bacteria  surviving  pasteurization  are,  for  the 
most  part,  the  quick  growing  bacteria  of  putrefaction 
which  are  inhibited  in  raw  milk  by  the  lactic  acid  bac- 
teria, but  in  pasteurized  milk  they  multiply  very  fast  and 
undoubtedly  they  are  capable  of  generating  poisonous 
substances.     It  has  been  suggested,  therefore,  that  a 
pure  culture  of  lactic  acid  bacteria  be  added  to  milk 
after  pasteurization  in  order  to  check  the  bacteria  of 
putrefaction. 

5.  In  purchasing  pasteurized  milk,  one  cannot  tell  if 


NVMBER  OF  SAMPLES 


j.n  L  JHJir.rt  \jr    JJA\  i  I^J\IA  ijj   j.  v^.^. 

Ordinary  whole  milk 

Pasteuriz'd  whole  milk 

0-10 

_ 

2 

10-50 

- 

_ 

100-500 

- 

2 

500-1,000 

- 

4 

1,000-5,000 

- 

1 

5,000-10,000 

- 

10 

10,000-20,000 

- 

6 

20,000-50,000 

- 

12 

50,000-100,000 

- 

7 

100,000-1,000,000 

7 

66 

1,000,000-5,000,000 

1 

20 

5,000,000-10,000,000 

- 

9 

Above  10,000,000 

1 

3 

Total  number  of  samples  .  .  . 

9 

142 

it  be  fresh  or  old  and  cannot  determine,  from  its  appear- 
ance, if  putrefaction  has  begun  or  if  only  a  few  bacteria 
are  present.  That  this  objection  to  the  sale  of  pasteur- 
ized milk  is  valid,  is  shown  by  the  Copenhagen  health 


PASTEURIZATION 


141 


Commission,  in  its  report,  especially  that  for  1899,  on 
the  number  of  bacteria  in  pasteurized  milk,  as  compared 
with  the  number  in  unpasteurized  milk. 

It  is  evident  that  these  figures  do  not  seem  to  favor 
pasteurized  milk,  and  the  situation  is  still  less  favorable 
if  one  considers  that  the  bacteria  in  raw  whole  milk  are 
chiefly  lactic  acid  bacteria,  while  in  pasteurized  milk 
the  greater  part  consist  of  bacteria  of  putrefaction.  The 
figures  above  cited  for  the  year  1899  are  especially  high, 
but  the  summary  given  below  is  made  from  examina- 
tions of  pasteurized  milk  extending  through  a  period  of 
several  years : 37 


NUMBER  OF  COLONIES  IN 

1  c.c. 

1896 

1897 

1898 

1899 

1900 

Below  100,000 

22 

26 

12 

44 

40 

100,000-1,000,000 

1 

5 

19 

66 

39 

Above  1,000,000 

- 

1 

17 

32 

26 

Total  number  of  samples 

23 

32 

48 

142 

105 

This  increase  in  the  number  of  strongly  infected  sam- 
ples occurs  coincidently  with  the  equipment  of  many 
milk  establishments  for  the  production  of  "  pasteur- 
ized "  milk  and  apparently  without  such  careful  direc- 
tion as  to  make  it  certain  that  the  whole  quantity  of 
milk  was  really  heated  to  the  required  temperature ;  that 
this  was  the  case  is  indicated  by  the  result  of  investiga- 
tions of  the  health  commission  in  the  year  1899,  which 
show  that  of  36  samples  of  pasteurized  cream  2,  and  of 
389  samples  of  pasteurized  milk  23  could  not  stand  the 


37  Stadslaegens  Aarsberetninger  (Annual  Report  of  the  City  Phy- 
sician ) .    Copenhagen. 


142  MILK  HYGIENE 

Storch  test,  which  showed  that  they  had  not  been  heated 
to  80°  C.  (176°  F.). 

When  we  compare  the  advantages  and  disadvantages 
it  will  be  found  that  there  is  serious  doubt  as  to  whether 
it  is  advisable  to  endeavor  to  obtain  general  pasteuriza- 
tion of  market  milk,  as  has  been  suggested  by  many.  A 
well  organized  and  well  conducted  large  milk  business 
may  be  in  position  to  carry  out  pasteurization  with 
safety  and  to  obtain  all  the  various  advantages  that 
result  from  this  process  but,  undoubtedly,  it  would  be 
necessary  for  the  great  majority  of  establishments  to 
be  kept  under  comprehensive,  strict  and  expensive  con- 
trol by  the  health  authorities  which,  even  then,  could 
scarcely  be  effective. 

II.    STERILIZATION 

By  sterilization  of  milk  is  understood  a  long  contin- 
ued boiling,  or  heating  to  a  temperature  above  the  boil- 
ing point  as  105°  to  110°  C.  (220°  to  230°  F.).  The 
superiority  that  is  claimed  for  sterilization  over  pasteur- 
ization is  that  all  of  the  bacteria  are  killed  and  the  milk, 
consequently,  will  keep  for  an  unlimited  time.  But 
nearly  all  the  examinations  of  " sterilized  milk"  bought 
in  the  market,  that  have  been  made,  up  to  the  present 
time,  have  shown  that  the  milk  is  not  sterile  but  con- 
tains the  spores  of  bacteria.  On  the  whole,  sterilization 
offers  no  special  advantage  over  pasteurization,  on  ac- 
count of  the  unpleasant  taste  of  sterilized  milk,  due  to 
changes  in  the  albumen  and  lactose,  and  on  account  of 
the  greater  expense  connected  with  it.  Sterilization  has 
the  advantage  only  when  it  is  a  question  of  keeping  the 
milk  a  long  time  or  transporting  it  a  long  distance,  and 
in  this  case  the  principle  followed  is  essentially  the 
same  as  that  followed  in  the  preparation  of  Dreserves  in 


STERILIZATION 


143 


hermetically  sealed  cans.  Considerable  advance  has 
been  made  in  recent  years  in  regard  to  the  preparation 
of  such  preserved,  canned,  milk,  in  that  the  boiled  and 


FIG.  10. 


Kleemaim's  high-pressure  pasteurizer  and  regenerative  heater,   a,  water  of  condensation 

b,  to  the  cooler. 

burnt  taste  has  been  prevented  by  pumping  the  air  out 
of  the  milk  before  heating  it  and  by  the  exclusion  of 
oxygen  during  heating,  so  that  a  high  temperature  is 
possible  and  a  safer  sterilization  is  accomplished  without 
seriously  affecting  the  taste.  Another  difficulty  which 
it  has  been  necessary  to  contend  with,  the  separation  of 
cream,  and  of  butter  formation  during  storage,  seems 
by  degrees  to  have  been  overcome. 

For  the  purpose  of  sterlizing  milk,  instead  of  the 
usual  apparatus  built  according  to  the  Fjord  system, 
tightly  closed  machines  are  used,  so  that  the  tempera- 
ture of  the  milk  can  be  raised  above  the  boiling  point, 
and  through  these  the  milk  is  forced  by  means  of  a  small 


144 


MILK  HYGIENE 


pump.  There  is  a  large  number  of  such  machines.  In 
Germany  they  are  commonly  used  for  simple  pasteuriza- 
tion. Of  the  machines  most  used  in  recent  years,  the 


FIG.  11. 


Section,  to  show  construction  of  apparatus  shown  in  Fig.  10.    a,  entrance  for  milk;   6, 
exit  for  milk  ;  c,  steam-chamber ;  d.steam-opening ;  e,  safety-valve. 


so-called  i  i  regenerative  heater  ' '  is  to  be  commended  be- 
cause it  saves  much  steam.  It  is  built  according  to  the 
principle  that  the  hot  milk  flows  past  the  entering  cold 


STERILIZATION 


145 


milk  (only  a  thin  metal  plate  separating  them)  so  that 
both  streams  of  milk  have  opposite  directions ;  by  this 
means,  there  is  the  advantage  that  the  hot  milk,  even  be- 
fore it  leaves  the  sterilizer,  is  somewhat  cooled  without 
expense,  while  the  cold  milk  gains  quite  a  little  heat  be- 
fore it  is  heated  by  the  action  of  the  steam.  In  this  way, 


FIG.  12. 


Mor's  regenerative  milk-heater. 

steam,  as  well  as  ice,  is  saved.  Machines  built  in  accord- 
ance with  this  principle  differ  much  in  appearance. 
Some,  for  example  the  apparatus  shown  in  Fig.  10,  which 
is  one  of  the  newest,  consists  really  of  two  parts,  the  ster- 
ilizer proper  (the  "  high  pressure  pasteurizer  ")  and  an 
apparatus  quite  similar  ("  the  regenerative  heater  ") 
10 


146  MILK  HYGIENE 

in  which  the  stream  of  warm  milk  works  upon  the  incom- 
ing cold  milk.  Both  parts  have  the  same  construction, 
which  is  easily  seen  from  Figs.  10  and  11.  Other  ma- 
chines of  this  kind  (for  example,  Mor's  regenerative  milk 
heater,  Fig.  12),  are  simpler  in  that  both  processes  take 
place  in  the  same  machine.  For  sterilizing  milk  meas- 
ured into  bottles,  machines  which  are  described  and 
figured  on  pages  136  and  137  (Fig.  9)  are  used. 


PART    V. 


THE    USE    OF    MILK    FOR    INFANTS 


THE  advantages  of  milk  as  a  general  food  for  man 
are  so  well  known  that  no  further  discussion  is  neces- 
sary ;  but  the  special  use  of  milk  for  infants,  as  a  sub- 
stitute for  mother's  milk,  offers  certain  points  of  inter- 
est which  merit  further  consideration.  It  is  logical  first 
to  review  the  behavior  of  milk  and  the  changes  that 
occur  in  it  during  digestion. 

Under  the  influence  of  the  gastric  juice,  the  proteids 
undergo  a  process  of  splitting  up  in  the  stomach.  The 
albumin  and  globulin  are  first  changed  into  syn- 
tonin  and  then  separated  into  albumoses  and,  probably, 
peptone.  Casein  behaves  somewhat  differently.  It  is 
transformed  by  the  hydrochloric  acid  of  the  gastric  juice 
into  an  acid  calcium  salt  and  then,  under  the  influence  of 
rennin,  it  undergoes  a  change,  during  which  whey  albu- 
min is  formed,  into  calcic  paracasein,  which  separates  as 
a  curd.  The  calcic  paracasein  is  then  split  by  pepsin  into 
albumin  and  paranuclein  (pseudoneuclein)  which  is  pre- 
cipitated but  which  is  afterwards  dissolved  by  the  pro- 
longed action  of  the  gastric  juice,  being  broken  up  into 
an  albumin-like  material  and  phosphoric  acid.  The  albu- 
mins that  are  formed  by  splitting  of  the  casein  are  later 
changed  into  albumoses  (caseoses)  and  peptone.  Ac- 
cording to  recent  investigations  it  appears  that  these 
substances  may  undergo  still  other  changes  before  they 
are  absorbed.  Through  the  action  of  rennin,  an  albu- 
min-like substance  (plastein)  is  formed  and  through  the 

147 


148  MILK  HYGIENE 

action  of  an  intestinal  ferment  (erepsin)  the  splitting 
of  peptone  is  continued  into  di-  and  mon-amido  acids. 
Little  is  known  as  to  the  resorption  and  use  of  these 
substances. 

There  is  a  difference  of  opinion  regarding  the  fate 
of  the  milk  sugar;  some  think  it  is  absorbed  from  the 
intestines  unchanged,  but  others  are  convinced  that  it  is 
first  inverted  into  dextrose  and  galactose.  The  absorp- 
tion takes  place  more  slowly  than  is  the  case  with  glu- 
cose, maltose  and  cane  sugar. 

The  absorption  of  milk-fat  takes  place  as  that  of 
other  fats,  with  a  preceding  saponification. 

It  is  well  known  that  cow's  milk  is  being  used  more 
and  more  as  food  for  infants  and  for  small  children.  As 
a  substitute  for  mother's  milk,  there  are  some  objections 
to  it,  however,  and  if  used  for  nursing  babes,  it  must 
receive  especial  treatment.  This  is  on  account  of  the 
fact  that  it  differs  materially  in  chemical  composition 
from  human  milk  and  that  it  constantly  contains  micro- 
organisms, and,  sometimes,  even  pathogenic  forms. 

The  differences  in  composition  of  human  milk  and 
cow's  milk  are  shown  by  the  averages  given  below: 

Water.  Casein.        Albumin.         Fats.  Lactose.        Salts. 

Woman's  milk...  87.92  0.58  0.52  3.43  7.12  0.2 

Cow's  milk 87.75  3.00  0.50  3.40  4.60        .5075 

[Human  milk  appears  to  vary  more  in  composition 
than  cow's  milk.  This  may  be  due  in  part  to  the  greater 
difficulty  in  obtaining  a  fair  sample  than  is  the  case  with 
cow's  milk.  It  is  known,  for  example,  that  the  compo- 
sition of  the  fore  milk  and  the  strippings  differ  consid- 
erably, and  if  small  samples  of  milk  are  drawn  from  a 
cow's  udder  at  irregular  times  during  the  day,  before 
and  after  regular  milkings,  the  samples  will  be  of  very 
different  composition.  Besides  this,  the  less  regular  life 


MILK  FOR  INFANTS  149 

of  the  woman  and  the  nervous  influences  to  which  she  is 
subject  may  tend  to  make  her  milk  more  variable  than 
that  of  the  even-going  cow. 

The  figures,  however,  that  are  given  in  the  above 
table  show  less  proteids  than  were  found  by  most  of 
the  leading  authorities.  The  average  composition  of 
woman's  milk,  as  determined  by  a  large  number  of 
analyses,  is  given  by  Richmond  as  follows : 

Water.        Proteids.         Fat.         Lactose.         Ash. 
Woman's  milk 88.2  1.5  3.3  8.8  02. 

Johanssen,  however,  found  but  1.1  per  cent,  of  pro- 
teids, as  an  average  for  25  samples,  thus  agreeing,  in 
this  respect,  with  the  figures  given  on  page  148  which 
are  from  Gottlieb.  L.  P.] 

The  first  thing  to  be  considered  is  that  the  quantity 
of  total  proteids  in  cow's  milk  is  more  than  three  times 
[or  more  than  twice]  the  quantity  in  human  milk,  so 
that  a  child  nourished  with  cow's  milk  has  apparently  a 
considerably  greater  nitrogen  assimilation  than  a  child 
nourished  in  the  natural  way.  It  is  not  known  with  cer- 
tainty what  significance  this  has  for  the  health  of  the 
child,  but  it  is  not  safe,  off  hand,  to  conclude  that  the 
highly  nitrogenous  diet  is  advantageous.  Moreover,  the 
chief  part  of  the  protein  of  cow's  milk  consists  of  a 
casein,  which,  in  contrast  with  the  casein  of  human  milk 
(the  proteids  of  human  milk  do  not  give  a  curd  with  ren- 
net), is  precipitated  in  the  stomach  as  large  curds  and  in 
a  form  that  apparently  makes  it  less  digestible. 

Great  importance  has  been  attributed  by  some  to  the 
fact  that  human  milk  often  contains  more  fat  than  cow's 
milk  and,  it  is  affirmed,  on  this  account  the  nutritive 
value  of  human  milk  is  greater  than  cow's  milk.  But 
since  we  know  that  the  fat  content  of  human  milk  is  sub- 
ject to  great  variation  (for  individual  peculiarities  see 
page  24)  no  particular  importance  can  be  attributed,  in 


150  MILK  HYGIENE 

general,  to  this  difference.  On  the  other  hand,  the  fact 
must  be  considered  that  the  fats  in  the  two  kinds  of  milk 
differ  somewhat  chemically,  and  that  cow's  milk  contains 
much  more  volatile  fat  (butyric  acid)  than  human  milk. 
These  other  important  conditions  should  be  mentioned : 
the  decided  different  proportions  of  lactose  which, 
doubtless,  is  of  value  in  the  nourishment  of  the  child,  and 
the  small  quantity  of  lecithin  in  cow's  milk,  to  which 
great  importance  is  now  ascribed  in  metabolism.  It  is 
doubtful  if  the  greater  quantity  of  citric  acid  and  of 
inorganic  salts  in  cow's  milk  has  an  unfavorable  influ- 
ence on  the  nourishment  of  the  child. 

Many  attempts  have  been  made  to  correct  the  defects 
of  cow's  milk  and  to  make  it  a  more  appropriate  food 
for  infants. 

By  diluting  cow's  milk  with  water,  the  percentage 
of  salt  is. proportionately  decreased  so  that  the  casein 
coagulates  in  the  stomach  in  flakes,  just  as  the  casein  of 
human  milk,  and  at  the  same  time  there  is  a  proportion- 
ate diminution  in  the  percentage  of  the  total  proteids. 
But  there  is  also  a  decrease  in  the  quantity  of  albumin 
as  well  as  of  the  other  ingredients  of  great  nutri- 
tive importance — lecithin,  lactose  and  fat — which  is 
decidedly  disadvantageous.  In  order  to  remedy  this, 
the  milk  is  often  diluted  with  barley-  or  oat-water  or  the 
proper  quantity  of  milk-  or  grape-sugar  is  added. 
Others  have  used  cream  diluted  with  water;  by  this 
means  an  appropriate  quantity  of  protein  and  fat  can 
be  had,  and  since  fat  may  be  substituted  for  lactose,  the 
deficiency  of  the  latter  makes  little  difference. 

To  make  cow's  milk  approach  human  milk  more 
closely,  and  to  make  it  more  easy  of  digestion  many 
methods  of  preparation,  some  of  them  rather  complex, 
have  been  proposed,  and  some  have  been  used  commer- 
cially. The  following  are  examples  of  such  preparations : 


MILK    FOR    INFANTS  151 

"Gartner's  fat  milk  "  is  prepared  in  the  following 
way:  cow's  milk  is  diluted  with  water  to  such  an  extent 
that  the  casein  content  corresponds  to  human  milk,  then 
it  is  so  centrifuged  that  the  milk  flowing  from  the  cream 
tube  has  a  fat  content  which  agrees  with  that  of  human 
milk.  The  milk  is  put  into  bottles  and  sterilized.  The 
composition  of  the  "  fat  milk  "  may,  of  course,  be 
changed  at  will ;  the  average  composition  of  such  a  prep- 
aration made  in  Germany  is :  fat,  3.7  per  cent. ;  proteids, 
1.5  per  cent. ;  lactose,  2.2  per  cent. 

"  Voltmer's  mother's  milk  "  is  the  name  given  to  a 
milk  preparation  that  is  sometimes  marketed  in  the  form 
of  "  milk/'  and  sometimes  is  condensed  and  sold  in 
cans.  The  preparation  is  somewhat  complicated;  fresh 
centrifuged  cow's  milk  is  heated  to  100°  C.  (212°  F.) 
and  distilled  water,  cream  and  sugar  are  added  to  it  in 
such  quantity  that  the  content  of  proteids,  fat  and  sugar 
correspond  to  human  milk;  the  mixture  is  now  exposed 
to  the  action  of  pancreas  ferment  which  process  changes 
the  casein  into  albumoses.  The  preparation  is  sterilized 
at  102°  to  105°  C.  (215.6°  to  221°  F.)  or  evaporated 
and  poured  into  cans  which  are  sterilized  after  solder- 
ing. According  to  several  analyses,  the  composition  of 
the  commercial  product  is,  approximately:  fat,  2.3  per 
cent.;  proteids,  1.8  per  cent,  (about  three-fourths  of 
this  is  albumose) ;  sugar,  6.2  per  cent.;  and  salt,  0.4 
per  cent. 

"Backhaus's  infants'  milk"  is  similarly  prepared. 
The  cream  is  separated  by  the  centrifuge ;  the  skimmed 
milk  is  heated  to  40°  C.  (104°  F.)  and  rennet  and  trypsin 
are  added.  In  the  course  of  half  an  hour  the  precipi- 
tated cheesy  mass  is  filtered  out;  by  this  means  a  part 
of  the  casein  can  be  taken  out,  while  the  rest  is  trans- 
formed into  easily  digestible  albumoses.  The  action  of 
the  ferments  is  stopped  by  heating,  and  cream  and  sugar 


152  MILK  HYGIENE 

of  milk  are  now  added.  The  preparation,  which  is  mar- 
keted in  a  sterilized  condition,  has  been  widely  recog- 
nized. Its  composition  may  easily  be  varied.  For  small 
children  a  preparation  of  about  the  following  composi- 
tion is  made:  fat,  3.1  per  cent.;  casein,  0.6  per  cent.; 
albumin,  1.0  per  cent. ;  lactose,  6  per  cent. ;  ash,  0.4  per 
cent. 

Gottlieb  has  proposed  that  sweet  whey,  cream,  sugar 
of  milk  and  lime  water  may  be  mixed  together  in  such 
proportions  that  the  composition  of  the  mixture  will 
closely  resemble  human  milk. 

["  Modified  milk  "  as  developed  and  prepared  by 
the  Walker-Gordon  Laboratory  Company,  with  the 
scientific  aid  of  Dr.  T.  M.  Eoach,  has  been  in  use  in  the 
larger  cities  of  America  and  in  London  for  a  number 
of  years;  it  was  first  prepared  and  sold  in  Boston  in 
1891.  Such  milk  is  dispensed  upon  physicians'  prescrip- 
tions, and  is  prepared  by  mixing  whole  milk,  cream, 
whey,  skim  milk,  lactose  and  water  or  other  substances, 
if  ordered,  as  lime  water,  starch,  barley-water,  etc.,  in  the 
proportions  required  to  give  accurately  the  desired  per- 
centages of  protein,  fat,  sugar,  etc.  It  is  dispensed  in 
round  bottles  ("  tubes  ")  each  of  which  contains  suffi- 
cient milk  for  a  single  feeding.  The  bottles  are  plugged 
with  cotton-wool.  The  milk  is  produced  on  farms  be- 
longing to  or  under  the  control  of  the  company  and  most 
exacting  precautions  are  taken  to  protect  it  from  con- 
tamination. 

The  milk  is  served  raw,  pasteurized  or  sterilized,  as 
ordered.  Usually  it  is  pasteurized  and  if  the  proteids 
consist  chiefly  of  those  present  in  whey,  the  tempera- 
ture reached  during  pasteurization  is  not  permitted  to 
exceed  155°  F.  By  means  of  modified  milk  the  nutritive 
requirements  of  the  individual  child  can  be  supplied. 
L.P.] 


MILK   FOE    INFANTS  153 

Many  special  preparations  similar  to  the  above  have 
been  used  abroad  and  have  received  the  approval  of 
pediatrists.  In  Denmark,  however,  they  are  used  but 
little  and  they  will  never  have  a  very  broad  field  on  ac- 
count of  their  high  price. 

In  France,  asses'  milk  is  quite  commonly  used  as  a 
substitute  for  human  milk  and  in  Dresden  an  establish- 
ment has  been  started  for  the  production  of  asses'  milk, 
which  is  desired  partly  because  of  its  great  similarity  to 
human  milk  and  partly  because  of  its  favorable  effect 
in  indigestion  of  children.  On  account  of  the  small  milk 
yield  of  the  donkey,  this  milk  is  much  too  expensive  to  be 
used  generally.  For  the  same  reason,  mare's  milk  has 
been  used  in  some  places,  but  only  to  a  limited  extent. 

Goat's  milk  has  been  suggested  as  food  for  infants, 
and  large  herds  of  goats  have  been  maintained  in  some 
places  for  this  purpose — principally  on  account  of  fear 
of  tuberculous  infection  from  cow's  milk.  The  prevalent 
opinion  of  the  infrequency  of  tuberculosis  in  goats  is 
untenable,  since  they  are  very  easily  infected  and  may 
suffer,  just  as  cows  do,  with  udder  tuberculosis.  There- 
fore, there  is  no  reason  to  prefer  goat's  milk  to  cow's 
milk. 

In  by  far  the  majority  of  cases  in  which  the  mother 
has  not  enough  milk,  or  her  child  will  not  nurse,  cow's 
milk  is  used  as  a  substitute.  The  question  has  often  been 
discussed  as  to  whether  and,  if  so,  what  special  require- 
ments should  be  made  for  milk  intended  for  infants,  and 
different  answers  are  given.  It  was  formerly  thought 
that  the  composition  of  the  cow's  food  had  a  marked 
influence  on  the  chemical  composition  of  her  milk,  and 
upon  its  character,  and  on  account  of  this  opinion  it  was 
formerly  required  in  Germany  that  cows  kept  for  this 
purpose  must  be  fed  nothing  but  dry  food  the  entire 
year.  The  price  of  such  milk  has  been  considerably  in- 


154  MILK  HYGIENE 

creased  on  this  account.  In  Denmark  also,  similar, 
though  less  strict,  requirements  were  made  for  the  pro- 
duction of  milk  for  infants.  During  recent  years,  how- 
ever, views  concerning  the  effect  of  the  forage  on  the 
quality  of  the  milk  have  changed  materially,  and  it  has 
been  observed  by  many  that  babies  have  been  fed  with- 
out discoverable  detriment  on  milk  from  cows  fed  with 
green  fodder,  turnips,  oil  cakes,  etc.,  and,  indeed,  in  some 
instances,  with  brewery  grains.  There  does  not  appear 
to  be  adequate  ground  for  the  requirement  that  cows 
kept  to  produce  nursery  milk  should  be  restricted  to  this 
one  sided  diet.  On  the  other  hand,  there  is  need  for  an 
active  control  of  the  sanitary  conditions  of  the  produc- 
ing herd,  for  the  public  must  be  assured  that  milk  sold 
at  a  high  price  especially  for  the  use  of  infants  may  be 
fed  to  them  without  danger  of  a  grave  infection  of  some 
kind.  The  nature  of  the  requirements  which,  in  our 
judgment,  should  be  made  concerning  the  production, 
handling  and  sale  of  "  nursery  milk  "  are  considered 
later. 

The  mortality  among  children  during  the  first  year 
of  life  is  very  significant.  In  Norway  and  Sweden,  from 
1891  to  1895,  on  the  average,  10  per  cent,  died  each  year ; 
in  Denmark,  14  per  cent.;  in  Finland  and  Switzerland, 
15  per  cent. ;  in  Prussia,  20.5  per  cent. ;  in  Baden,  22  per 
cent. ;  in  Wiirtemberg,  25  per  cent. ;  in  Bavaria,  27  per 
cent. ;  and  in  Saxony,  28  per  cent.,  while  the  mortality  in 
Austria  and  Hungary  is  25  to  28  per  cent.  The  mor- 
tality is  greatest  in  large  cites,  somewhat  less  in  small 
cities  and  least  in  the  country. 

Different  cities  show  different  death  rates;  for  ex- 
ample, from  1886  to  1895,  on  an  average,  each  year  13 
per  cent,  of  the  children  less  than  one  year  old  died  in 
Lyons,  15  per  cent,  in  Christiania,  16  per  cent,  in  Paris 
and  London,  and  the  death  rate  in  Berlin  reached  25.3 


MILK    FOE    INFANTS  155 

per  cent.,  in  Budapest  28  per  cent.,  in  Munich  31.4  per 
cent,  and  in  Ingolstadt  even  40.9  per  cent.38 

In  Copenhagen,  the  mortality,  during  the  first  year 
of  life,  has  decreased  significantly;  1877  to  1886,  20.83 
per  cent,  died  each  year;  in  the  next  decade  19.04  per 
cent.,  during  1897  to  1899,  17.87  per  cent.,  while  only 
15.55  per  cent,  died  in  1900.  Infant  mortality  is  also 
on  the  decrease  in  the  provincial  cities,  and  this  is 
certainly  true  of  many  large  cities  abroad. 

A  comparison  of  normally  fed  children  with  chil- 
dren fed  on  raw  or  prepared  cow's  milk,  shows  a  far 
greater  death  rate  among  the  latter.  If  the  cases  of  dis- 
eases and  death  are  arranged  according  to  the  separate 
months,  it  is  noticed  that  in  most  cities  there  is  a  marked 
increase  of  deaths  in  July  and  August  and  a  propor- 
tionate decrease  in  September,  and  this  increased  mor- 
tality pertains  almost  exclusively  to  children  fed  arti- 
ficially. 

By  far  the  greater  part  of  the  fatal  diseases  are  af- 
fections of  the  stomach  and  the  intestines  as  catarrh, 
colics  and  cholera  infantum.  Although  the  causal  con- 
ditions are  not  fully  explained,  it  may  be  stated  that 
cow's  milk  appears  to  induce  a  predisposition  to  intes- 
tinal infections,  on  account  of  its  varying  and  hetero- 
geneous composition.  The  diseases  are  to  be  attributed 
to  the  action  of  microbes ;  possibly  in  some  cases  to  bac- 
teria that  have  formed  toxic  substances  during  their 
development  in  the  milk,  but  in  the  greater  number  of 
cases  it  is,  doubtless,  a  question  of  the  presence  of  patho- 
genic microbes  in  milk  (streptococci,  proteus-  and  colon 
forms).  Therefore,  milk  intended  for  infants  should  be 
sterilized.  Opinions  differ  as  to  whether  heating  with 
steam  for  an  hour  (Soxhlet's  method)  is  to  be  preferred 

38  These  figures  are  taken  from  Ohlens'  Die  Milch  und  ihre  Beden- 
tung,  1903. 


156  MILK  HYGIENE 

to  brief  boiling  or  to  pasteurization,  since  it  is  thought 
that  long  cooking  affects  the  digestibility  of  the  casein. 

Through  the  zealous  efforts  of  physicians,  it  has  been 
possible,  during  recent  years,  to  cause  the  general  ac- 
ceptance of  the  practice  of  sterilizing  milk  for  infants 
and  the  reports  show  that  this  has  had  a  favorable  influ- 
ence in  preventing  disease  and  death. 

There  are,  however,  some  children  ivith  ivhom  cooked 
cow's  milk  does  not  agree,  as  it  causes  continual  indiges- 
tion and  loss  of  weight  so  that,  indeed,  when  six  months 
old  they  may  weigh  less  than  at  birth  (infantile  atro- 
phy). This  condition  is  often  improved  at  once  if  a  wet 
nurse  is  procured  for  the  child  or  if  asses '  milk  is  used ;  or 
a  change  to  raw  cow's  milk  may  lead  to  quick  recovery. 
An  explanation  of  these  different  effects  of  cooked  or 
raw  cow's  milk  cannot  be  given  here,  since  there  is  no 
convincing  reason  for  the  opinion  that  cooked  milk  is 
harder  to  digest  than  raw.  Possibly  the  favorable  effect 
of  raw  milk  can  be  attributed  to  the  presence  of  sub- 
stances antitoxic  to  some  of  the  poisons  absorbed  from 
the  intestinal  canal,  which  antitoxins  are  destroyed  by 
heating  the  milk.  [In  America,  the  balance  of  opinion 
among  pediatrists  appears  to  be  in  favor  of  clean,  raw 
milk,  specially  produced,  of  low  bacterial  content  and 
from  a  reliable  source  ("  certified  milk  ") ;  or  milk  that 
has  been  pasteurized  at  a  moderate  temperature  (155° 
to  185°  F.)  and  that  has  not  been  boiled.  L.  P.] 


PART   VI. 


PUBLIC    CONTROL  OF  THE  PRODUCTION 
AND  HANDLING  OF  MILK 


NATUKALLY  there  are  great  differences  in  different 
countries  in  the  way  cities  are  supplied  with  milk  and  in 
the  manner  in  which  it  is  handled  after  it  reaches  the 
cities.  In  general,  it  may  be  said  that  there  is  no  diffi- 
culty in  supplying  small  towns,  as  herds  are  sometimes 
to  be  found  within  their  limits  and  usually  enough  milk 
is  brought  in  from  the  immediately  outlying  districts. 
It  is  different  with  the  larger  cities  and,  with  respect  to 
them,  the  milk  business  has  been  greatly  changed  dur- 
ing the  last  20  to  30  years.  The  conditions  in  Copenha- 
gen may  serve  as  an  example,  as  they  do  not  differ  mate- 
rially from  those  found  in  other  large  European  cities. 
Copenhagen  was  once  supplied  with  milk  chiefly  from 
the  brewery  herds  and  other  herds  within  the  city,  and 
by  farmers  from  the  adjoining  country,  who  delivered 
milk  to  their  own  regular  customers  in  the  city ;  now  the 
conditions  are  wholly  changed. 

The  continual  growth  of  the  city  and  the  constantly 
increasing  hygienic  demands  have  caused  the  almost 
complete  discontinuance  of  cattle  keeping  within  the 
city,  and  proximity  to  the  large  city  has  greatly  affected 
the  character  of  the  farming  nearby,  so  that  the  breed- 
ing of  cattle  and  dairying  have  fallen  off.  On  the  other 
hand,  on  account  of  easy  transportation  by  railroad, 
farmers  living  at  quite  a  distance  can  deliver  their  milk 
to  advantage  in  Copenhagen,  and  at  this  time  the  city  is 

157 


158  MILK  HYGIENE 

supplied  with  milk  not  only  from  the  island  .upon  which 
it  is  situated  but  also  from  the  surrounding  islands. 
This  facility  of  transportation  by  railroad  and  boat  has 
led  to  the  establishment  of  milk  depots  that  receive  the 
milk  from  the  farms,  handle  it  appropriately  and  deliver 
it  to  their  customers,  selling  it  either  from  established 
sales  places,  or  from  wagons. 

This  evolution  in  the  handling  of  milk,  which  has 
occurred  in  most  of  the  large  cities  of  other  countries  as 
well,  marks  an  important  advance  in  hygienic  methods. 
The  milch  herds  in  the  cities  and  the  retail  shops  con- 
nected with  them  were  very  often  the  source  of  grave 
epidemics ;  the  uncontrolled  sale  of  milk  by  small  farm- 
ers has  had  the  same  unfortunate  result,  and  there  is 
danger,  too,  in  the  small  shops,  as  the  limited  space  makes 
it  difficult  to  prevent  the  various  members  of  the  family 
from  coming  into  too  close  contact  with  the  milk  contain- 
ers and  with  the  milk  itself. 

Large  companies  are  better  able  to  bear  the  expense 
resulting  from  the  observance  of  hygienic  requirements, 
and  the  sanitary  control  of  these  may  be  much  more 
easily  effected  than  in  the  case  of  numerous  small  con- 
cerns. It  is  to  be  observed  also  that  many  of  the  large 
milk  establishments  have  voluntarily  adopted  standards 
for  the  production  and  handling  of  milk  that  are  in  ad- 
vance of  requirements  of  the  health  authorities.  There 
are  no  proven  cases  of  milk  epidemics  traced  to  infec- 
tion through  milk  from  ivell  conducted  large  concerns; 
no  doubt  the  mixing  of  a  large  quantity  of  milk  lessens 
the  danger  of  infection,  since  usually  a  certain  amount 
of  infectious  material  is  necessary  to  produce  infec- 
tion. On  the  other  hand,  however,  the  mixing  together 
of  a  great  quantity  of  milk,  under  unfavorable  condi- 
tions, may  be  particularly  dangerous  because  if  a  milk 
epidemic  were  caused  it  would  be  very  widely  spread. 


HANDLING  OF  MILK  159 

A  strictly  enforced  control  is,  therefore,  no  less  neces- 
sary for  large  establishments  than  for  small. 

The  first  large  milk  company  established  in  Co- 
penhagen was  the  Copenhagen  Milk  Supply  Company 
which,  more  than  25  years  ago,  at  a  time  when  milk 
hygiene  was  still  on  a  low  plane  in  Denmark,  as  it  was 
abroad,  established,  voluntarily,  a  comprehensive  stand- 
ard covering  the  condition  of  health,  the  cleanliness  and 
the  feeding  of  the  herd,  the  health  of  the  milkers  and 
other  employees  and  the  proper  handling  of  the  milk. 
This  company  rapidly  developed  a  very  important  busi- 
ness and  has  been  imitated  in  Denmark  and  in  other 
countries.  Several  new  companies  have  made  even 
greater  advances  in  the  adoption  and  enforcement  of 
hygienic  requirements.  Moreover,  the  large,  well  organ- 
ized milk  companies  have  had  a  very  great  influence  in 
forcing  the  small  concerns  to  handle  their  milk  with 
much  greater  cleanliness  and  care. 

The  most  familiar  ways  of  retailing  milk  in  cities, 
are :  the  milk  is  drawn  and  sold  in  established  shops  or 
it  is  drawn  or  dipped  from  tanks  carried  on  wagons,  or, 
thirdly,  the  milk  is  first  bottled,  or  is  placed  in  cans  that 
are  closed  and  sealed.  The  last  method  is  decidedly  the 
best  and  it  is  now  rapidly  displacing  the  other  methods. 
When  milk  is  measured  out  on  the  street,  it  may  easily 
be  contaminated  by  dust  and  dirt  blown  about  by  the 
wind,  and  as  the  delivery  buckets  are  carried  from  one 
kitchen  to  another,  there  is  a  possibility  that  they  may 
carry  contagion.  This  method  of  delivery  is  also  at- 
tended by  the  possibility  of  defective  measuring,  etc., 
by  the  deliveryman. 

The  hygienic  requirements  that  should  be  established 
with  relation  to  the  milk  supplies  of  cities,  will  doubtless 
lead  to  a  further  change  in  the  milk  business  as  this  is 
apparently  going  more  and  more  into  the  hands  of  a 


160  MILK  HYGIENE 

few  large  companies  while  the  number  of  small  con- 
cerns is  stea'dily  decreasing. 

[In  America  this  tendency  toward  centralization  of 
the  business  is  very  marked  in  most  large  cities,  and 
especially  in  New  York  and  Boston.  The  reason,  how- 
ever, is  economic  and  is  similar  to  the  causes  for  con- 
solidation in  other  lines  of  trade.  L.  P.] 

Since  milk,  as  has  been  said,  can  acquire  harmful 
properties  in  different  ways,  since  its  composition  may 
vary  considerably,  and  since  it  may  be  adulterated  in 
many  ways,  the  milk  business  must  be  supervised  by 
public  authority,  under  appropriate  laws  or  ordinances. 
Formerly,  in  most  large  cities,  the  occasional  examina- 
tions had  reference  only  to  the  fat  content  of  the  milk 
(transparency  test,  determination  of  the  specific  gravity, 
etc.),  and  in  many  places,  even  at  the  present  time,  no 
further  progress  has  been  made.  But  our  present 
knowledge  makes  it  obvious  that  such  an  examination, 
in  comparison  with  the  standard  that  should  be  estab- 
lished to  guard  against  dangerous  milk,  has  relatively 
little  importance.  The  public  control,  therefore,  is  not 
to  be  limited  to  an  examination  for  adulteration  and 
souring  or  ' '  spoiling  ' '  of  milk  on  the  market,  but  must 
extend  to  the  production  and  the  care  and  treatment  of 
the  milk  (including  the  condition  of  health  of  those  per- 
sons who  come  into  direct  or  indirect  contact  with  it). 
The  enforcement  of  complete  regulations  for  this  pur- 
pose, of  course,  is  accompanied  with  great  difficulties, 
and  there  is  no  city  in  the  world  whose  measures  in  this 
respect  can  be  said  to  be  ideal.  A  point  to  be  avoided  in 
such  a  control  is  a  great  increase  in  expense  which  would 
raise  the  price  of  milk.  This  would  be  a  hardship  for  the 
public,  the  importance  of  which  from  the  economic  and 
hygienic  view  points,  must  not  be  underrated.  In  the 
inauguration  of  a  thorough-going  supervision  it  may 


HANDLING  OF  MILK  161 

be  necessary  to  interfere  considerably  with  the  methods 
of  producing  and  handling  milk  as  these  have  gradually 
developed.  Local  conditions  will  have  an  important  in- 
fluence on  the  establishment  of  a  system  of  control  and 
will  determine  the  rapidity  with  which  the  various  re- 
quirements can  be  fulfilled. 

General  laws  governing  the  production  and  handling 
of  milk,  are  lacking  in  most  countries.  Only  a  few  coun- 
tries (i.e.,  Portugal  in  1900)  have  enacted  such  laws  and 
there  is  not  much  evidence  as  to  the  practical  success  of 
these  requirements  for  a  whole  country.  In  a  large  num- 
ber of  the  cities  of  Europe  somewhat  detailed  regula- 
tions have  been  adopted  in  regard  to  the  milk  trade ;  but 
these  regulations,  even  in  the  same  country,  differ  very 
much.  Dresden  may  be  mentioned  as  an  example  of  a 
large  city  with  excellent  modern  regulations  for  the 
handling  of  milk.  (Published  July  31st,  1900,  with 
amendments  of  February  26th,  1901.)  In  order  to  estab- 
lish a  uniform  system  in  Prussia,  the  Prussian  govern- 
ment in  1899  published  a  circular  of  information  to  mu- 
nicipalities with  detailed  instructions  for  .a  judicious 
regulation  and  supervision  of  the  milk  trade.  In  many 
of  the  small  cities  there  is  either  no  control  at  all  or  a 
very  defective  one. 

[The  following  table  from  a  report  by  H.  E.  Alvord 
and  R.  A.  Pearson  on  the  milk  supply  of  200  cities  and 
towns  in  the  United  States  shows  the  subjects  of  most 
frequent  legislation  in  connection  with  market  milk  in 
126  cities,  the  milk  ordinances  and  regulations  of  which 
were  examined  with  especial  care.  The  most  popular 
subjects  for  legislation  are  readily  seen. 


11 


162 


MILK  HYGIENE 


SUBJECTS. 


NUMBER 
OF  CITIES 


SUBJECTS 


NUMBER 
OP  CITIES 


Dairies  : 

License  or  permit  required 

Special  authority  for  in- 
spections   

Pure  water  supply 

Drainage  of  barnyards  . . . 
Stables  : 

Proximity  to  other  build- 
ings   

Light 

Ventilation 

Floor  space 

Air  space 

Cleanliness 

Removal  of  manure 

Drainage 

Other  than  dairy  animals 
to  be  excluded 

Sanitary  milk  room 

Employees  : 

Personal  cleanliness 

Contagious  disease  (to  be 
reported) 

If  exposed  to  contagious 
disease . . 


Cows  : 

Provisions  for  examina- 
tion   

Diseased  cows 

Unwholesome  food  for- 
bidden   

Pure  water  supply 

Cleaning  cows 

Milk  rejected  at  calving 
time . . 


12 

58 

8 

12 


6 

15 
32 
15 
10 
47 
25 
17 

4 
14 

20 
15 
25 


58 
24 

77 
40 
27 

33 


Care  of  milk : 

Milk  vessels  to  be  nonab- 
sorbent  

Milk  vessels  to  be  thor- 
oughly cleaned 

Milk  to  be  promptly  re- 
moved from  the  stable. . 

Straining 

Cooling  and  aerating 

Conditions  of  storage 

Sale  of  milk: 

Licenses,  or  permits 

Licenses  to  be  publicly 
displayed 

Source  of  supply  to  be 
posted 

General  inspection  in  cities 

Signs  on  wagons 

Unsanitary  milk  prohib- 
ited  

Confiscation  of  impure 
milk 

Definite  standard  for  com- 
position   ) . 

Skimmed  milk  prohibited 

Skimmed  milk  permitted 
conditionally 

Bottling  at  farm 

Storage  of  milk  for  sale . . . 

Milk  tickets  to  be  used  but 


once 

Milk  wagons  to  be  covered 
Milk  wagons  not  to  carry 


Sellers  to  register  custom- 
ers  


55 
32 

11 
9 

15 
23 

92 
24 

14 
75 
79 

109 
30 

67 
12 

61 

8 

23 

16 
12 

5 

7 


L.  P.] 


HANDLING  OF  MILK  163 

While  the  establishment  of  milk  control  on  the  part 
of  the  public  leaves  much  to  be  desired,  private  initia- 
tive, as  mentioned  before,  has  led  to  significant  sanitary 
improvement,  in  that  large  stock  companies  have  been 
formed  in  many  cities  to  provide  sanitary  milk  and  have 
voluntarily  subjected  themselves  to  extra  expense  for 
guaranteeing  and  controlling  it.  In  some  respects,  this 
voluntary  control  far  surpasses  what  the  public  could 
impose  at  this  time.  Appendix  I  gives  the  require- 
ments of  the  youngest  company  in  Copenhagen  ("  Tri- 
folium  "),  which  shows  how  far  a  private  company  may 
carry  this  sanitary  control,  and  these  regulations  may 
well  serve  as  a  model  for  other  places. 

While  the  companies  referred  to  established  their 
own  requirements  and  determined  the  extent  of  the  con- 
trol to  which  they  submitted,  another  very  successful 
plan  has  been  inaugurated  in  Stockholm,  which  consisted 
in  the  establishment,  in  1885,  by  private  initiative,  of  a 
milk  commission  of  9  members,  including  4  physicians,  1 
veterinarian  and  1  chemist.  The  members  of  this  com- 
mission are  chosen  in  part  by  the  Board  of  Health  and 
in  part  by  the  Medical  Society.  This  commission  has 
outlined  a  comprehensive  control,  which  includes  all  who 
desire  it  and  who  are  ready  to  bear  the  expense  con- 
nected with  it.  The  business  advantages  of  this  control 
are  such  that  a  higher  price  than  usual  is  obtained  for 
the  milk  produced  under  it. 

Since  the  legal  requirements  in  the  different  cities 
vary  and  are  adapted  to  the  local  conditions,  it  is 
not  possible  to  give  a  concise,  epitomized  view  of 
existing  regulations ; 39  the  following,  however,  is  an 

39  For  a  review  of  the  local  milk  inspection  laws  of  the  United 
States  and  recommendations,  see  "  The  Milk  Supply  of  Two  Hundred 
Cities  and  Towns,"  by  H.  E.  Alvord  and  R.  A.  Pearson.  U.  S.  Dept. 
of  Agr.,  B.  A.  I.  Bulletin  No.  46,  Washington,  1903. 


164  MILK  HYGIENE 

attempt  to  define  the  requirements  which,  from  a  sani- 
tary standpoint,  are  to  be  considered  necessary  or 
desirable. 

In  order  to  be  effective,  the  legal  or  police  require- 
ments covering  the  milk  trade,  must  contain  detailed 
regulations  concerning: 

The  production  of  milk. 

The  care  and  handling  of  milk. 
'  The  prevention  of  adulteration. 

The  prevention  of  the  sale  of  tainted  or  damaged 
milk. 

In  respect  to  the  enforcement  of  these  regulations  in 
cities,  the  supervision  will  rest — at  least  in  Denmark — 
with  the  local  health  authorities,  and  preferably  with  a 
veterinarian  appointed  by  this  authority,  who  will  con- 
duct the  inspection  of  the  milk  establishments  with  the 
cooperation  of  the  police,  and  take  the  necessary  sam- 
ples for  further  examination.  In  small  cities,  the  inspec- 
tion of  the  production  of  the  milk  may  also  be  under- 
taken by  the  same  veterinarian;  but  in  the  larger  cities, 
as  a  rule,  this  is  left  to  the  local  veterinarians  in  the  coun- 
try, and  the  various  dealers  or  herd  owners  ar£  required 
to  furnish  certificates,  that  should  be  drawn  up  on  a 
prepared  blank  and  be  submitted  to  the  health  office  con- 
cerned. 

I.    REGULATIONS  REGARDING  THE   PRODUCTION 
OF  MILK 

Public  supervision  of  the  production  of  milk  presents 
great  difficulties  and  has  been  carried  out  in  but  a  few 
places.  In  the  ordinances  of  most  cities,  there  are  cer- 
tain requirements  pertaining  to  the  production  of  milk, 
but  their  enforcement  is  not  always  provided  for.  In 
several  cities  every  owner  of  cattle  who  delivers  milk  in 
the  city,  either  directly  or  indirectly,  is  obliged  to  appear 
before  a  public  authority  and  pledge  himself  to  observe 


REGULATION  OF  PEODUCTION  165 

the  existing  legal  requirements  or  those  that  may  be 
made  later,  and  especially  to  report  every  change  in  the 
make  up  of  his  herd.  This  is  a  good  arrangement.  The 
actual  observance  of  these  requirements  should  be  con- 
trolled by  frequent  visits  of  a  veterinarian  appointed 
by  a  central  authority  or  by  occasional  visits  of  the 
local  veterinarian,  but  the  latter  plan  is  not  so  satisfac- 
tory. 

Such  a  regulation  would,  of  course,  be  particularly 
difficult  in  large  cities  as,  for  example,  Copenhagen, 
which  receives  milk  not  only  from  a  very  large  number 
of  large  and  small  herds,  the  cows  in  which  are  often 
changed,  but  is  supplied  with  milk  from  a  large  part  of 
the  country.  On  tiie  other  hand,  the  regulations  men- 
tioned can  be  adopted  without  great  difficulty  in  small 
cities,  although  they  might  cause  dissatisfaction  at  first 
among  the  dairy  farmers.  In  most  of  the  larger  cities, 
up  to  the  present  time,  little  has  been  done  except  to 
publish  notices  in  regard  to  the  regulations  respecting 
the  production  of  milk,  but  no  reports  have  been  de- 
manded of  producers  and  no  special  control  has  been 
provided  to  enforce  these  regulations.  The  local  boards 
of  health  have  the  right  to  investigate  cases  which  are 
reported  and  if  necessary  to  forbid  the  sale  of  milk  from 
the  premises  involved. 

[In  the  United  States,  there  is  a  certain  amount  of 
dairy  farm  inspection  under  the  authority  of  the  states. 
In  Massachusetts,  herds  are  inspected  by  the  Cattle  Bu- 
reau of  the  Board  of  Agriculture,  in  Pennsylvania  by 
the  State  Livestock  Sanitary  Board,  on  request  from 
local  boards  of  health  that  their  milk  supplies  be  exam- 
ined into ;  in  several  states,  herds  and  premises  are  in- 
spected under  authority  of  the  State  Dairy  and  Food 
Commissioner,  the  Commissioner  of  Agriculture  or  the 
State  Board  of  Health.  In  no  state,  however,  is  there  a 


166  MILK  HYGIENE 

systematic  inspection  of  all  dairy  herds,  excepting  in 
Massachusetts,  where  the  inspection  is  made  for  the  pur- 
pose of  controlling  bovine  tuberculosis.  A  number  of 
cities,  on  the  other  hand,  require  periodical  inspection 
of  the  herds  from  which  they  obtain  their  milk  supply. 
L.  P.] 

The  control  to  which  a  number  of  large  milk  com- 
panies have  submitted  voluntarily,  either  from  philan- 
thropic motives  or  because  driven  to  it  by  competition, 
consists  chiefly  in  frequent,  regular  visits  from  vet- 
erinarians to  the  milk  producing  herds,  during  which 
not  only  the  conditions  of  health  of  the  cows  but  also 
their  food,  the  cleanliness  of  the  stables,  the  handling 
of  the  milk,  and  the  health  of  the  milkers  are  the  objects 
of  a  more  or  less  effective  supervision.  Some  establish- 
ments have  provided  a  separate  organization  for  super- 
vising the  health  of  the  employees.  It  is  self-evident 
that  the  methods  of  such  companies,  however  good  their 
private  supervision  may  be,  must  be  subject  to  the  supe- 
rior control  of  health  officers. 

[It  will  be  observed  that  the  author  dwells  not  so 
much  on  the  importance  of  the  recognition  of  infective 
organisms  in  milk  as  on  their  exclusion.  Unquestion- 
ably it  is  infinitely  better,  from  the  standpoint  of  the 
public  health^  to  prevent  the  contamination  of  milk  than, 
by  means  of  laboratory  examination,  to  discover  evi- 
dences of  contamination  in  a  sample  representing  a 
quantity  of  milk  that  has  already  been  consumed. 

Milk  is  not  a  food  that  is  kept  long ;  it  cannot  be  put 
away  in  storage  until  a  sanitary  examination  has  been 
made,  and  then  released  for  consumption,  or  destroyed, 
according  to  the  result  of  the  examination.  Only  the 
briefest  inspections  can  be  made  while  the  milk  is  en 
route  from  the  producer  to  the  consumer. 

The  supply  continues  as  a  flowing  stream,  and  is 


REGULATION  OF  PRODUCTION          167 

never  just  alike  at  different  times  or  places.  The  lab- 
oratory examination  of  a  milk  sample  gives  some  infor- 
mation as  to  the  condition  of  that  sample  and,  by  infer- 
ence, as  to  the  conditions  under  which  a  certain  quantity 
of  milk  was  produced  and  handled  on  a  given  day.  But 
some  of  the  contaminations  of  milk  that  are  most  dan- 
gerous cannot  be  detected  by  routine  examinations  in 
the  laboratory,  if  at  all,  excepting  by  their  effects  on  the 
consumer ;  among  such  contaminations  are  those  caused 
by  the  specific  organisms  of  tuberculosis,  typhoid  fever, 
diphtheria,  scarlet  fever  and  the  materies  morbi  of 
many  diseases  of  cows.  Therefore,  so  far  as  the  pre- 
vention of  the  infection  or  pollution  of  milk  is  concerned, 
it  is  more  important  that  the  milk  be  produced  under 
such  conditions  that  contamination  is  well  guarded 
against  than  to  know  the  condition  of  a  certain  quantity 
that  has  already  been  used. 

The  laboratory  examination  of  milk  is,  however,  of 
much  value  in  checking  and  controlling  the  accuracy  of 
farm  and  herd  inspections,  which  inspections  are  de- 
signed to  prevent  infection  and  pollution,  while  the  lab- 
oratory discovers  contaminations  that  have  already 
occurred. 

The  author's  position  on  this  general  subject  is  quite 
analogous  to  the  opinion  that  is  now  held  by  sanitarians 
in  regard  to  the  way  in  which  the  purity  of  the  water 
supply  should  be  obtained  and  insured ;  that  is,  by  clean- 
ing and  guarding  the  source. 

It  is  well  to  lock  the  stable  door  before  the  horse  is 
stolen.  But  it  has,  thus  far,  been  impossible  in  America, 
excepting  in  a  few  isolated  instances,  to  impress  the 
public  sufficiently  to  lead  to  the  establishment  of  a  sys- 
tematic inspection  of  the  sources  and  methods  of  hand- 
ling and  transporting  milk.  Eeasons  for  this  condition 
are,  the  paucity  of  specially  trained  men  for  this  ser- 


168  MILK  HYGIENE 

vice  and,  on  this  account,  the  difficulty  health  officers 
have  experienced  in  securing  inspectors  to-do  such  work 
in  a  satisfactory  way  and,  secondly,  the  expense.  A 
properly  equipped  dairy  farm  inspector  must  have  had 
special  training,  and  must  be  familiar  with,  and  be  able 
to  apply,  facts  from  pathology,  bacteriology,  zootechnics 
and  dairy  husbandry. 

Dr.  William  T.  Sedgwick  has  emphasized  the  impor- 
tance of  control  of  the  source  of  the  milk  supply,  to  pre- 
vent pollution,  as  follows : 40 

"  It  should  never  be  forgotten  that  if  water  were  to 
be  drawn,  as  milk  is,  from  the  body  of  a  cow  standing  in 
a  stable,  by  the  hands  of  workmen  of  questionable  clean- 
liness, and  then  stored  and  transported  over  long  dis- 
tances in  imperfectly  cleaned,  closed  cans,  being  further 
manipulated  more  or  less,  and  finally  left  at  the  doors 
at  an  uncertain  hour  of  the  day,  few  would  care  to  drink 
it,  because  its  pollution  and  staleness  would  be  obvious. 
It  is  clear,  moreover,  that  it  requires  and  deserves  more 
careful  treatment  than  water,  for  it  is  more  valuble, 
more  trusted  and  more  readily  falsified  or  decomposed.'' 

Dr.  Rowland  G.  Freeman  has  stated  his  opinion  as  to 
the  importance  of  controlling  the  source  of  the  milk  sup- 
ply, rather  than  to  attempt  to  determine  its  character  by 
bacteria  counts,  in  these  words :  "It  seems  to  me  that 
while  the  counts  of  bacteria  are  exceedingly  valuable  as 
an  exponent  of  cleanliness  and  proper  handling  of  milk, 
they  should  be  used  only  to  prevent  carelessness  at  the 
dairy  and  to  stimulate  better  methods  and  discipline. 

"  The  opinion  of  a  milk  commission  of  representa- 
tive men  (experts)  based  on  an  actual  knowledge  of  the 
management  of  the  dairy  is  of  vastly  more  value  to  the 


40  Sedgwick,    Principles    of    Sanitary    Science    and    the    Public 
Health.     New  York  and  London,  1902,  page  279. 


REGULATION  OF  PRODUCTION          169 

medical  profession  and  to  the  public  than  any  statement 
regarding  the  precise  number  of  bacteria  in  the  milk 
upon  any  given  day  or  days.  The  most  important 
things,  after  all,  are  such  a  regime  as  shall  make  con- 
tamination by  pathogenic  organisms  improbable,  and 
at  the  same  time  insure  that  the  milk  is  produced  under 
such  conditions  of  cleanliness  that  other  bacterial  con- 
taminations will  be  reduced  to  the  minimum. "  L.  P.] 

a.  The  condition  of  health  of  the  herd.  The  ideal 
requirement  that  only  milk  from  a  perfectly  healthy 
herd  may  be  marketed,  cannot  be  maintained.  The  pub- 
lic, therefore,  must  be  satisfied  to  demand  that  the  health  . 
condition  of  the  herd  is  such  that  its  milk  does  not  pos- 
sess injurious  qualities.  If  infectious  diseases  which  are 
transmissible,  through  milk,  to  man,  break  out  in  the 
herd,  the  sale  of  the  milk  should  be  forbidden  as  long  as 
danger  of  infection  be  present.  If  individual  cases  of 
infectious  or  other  diseases  occur  which  may  lead  to  the 
contamination  of  the  milk  of  the  affected  cows  by  patho- 
genic bacteria  or  toxins,  it  must  be  the  duty  of  the  owner 
to  prevent  this  milk  being  mixed  with  the  other  milk, 
and,  indeed,  wholly  to  prevent  its  use  as  food  for  man. 

Such  regulations  as  the  following  may  be  regarded 
as  necessary : 

The  use  of  the  milk  from  the  whole  herd  is  to  be  dis- 
continued if  foot-and-mouth  disease,  lung  plague  or 
anthrax  occur,  also  in  the  case  of  extended  outbreaks  of 
transmissible  infections  of  the  udder,  septic  enteritis, 
cowpox,  or  of  any  toxic  disease  of  a  large  part  of  the 
herd. 

The  milk  of  individual  cows  should  not  be  used,  and 
affected  animals  are  immediately  to  be  removed  from 
the  stable,  in  cases  of  tuberculosis  affecting  the  udder, 
the  uterus  or  the  intestines  and  when  the  lungs  are  so 
affected  as  to  occasion  physical  symptoms;  also,  milk 


170  MILK  HYGIENE 

from  cows  suffering  from  anthrax  or  rabies  (bitten  by 
affected  animals),  and  that  from  cows  with  mastitis, 
with  inflammation  of  the  uterus  and  retention  of  the 
afterbirth,  inflammation  of  the  intestines  or  severe 
diarrhoea,  and  with  severe  cellulitis  or  abscesses  and 
suppuratirig  wounds. 

Milk  should  not  be  used  from  coivs  suffering  from 
any  sort  of  febrile  disease  or  intoxication,  with  pox  or 
suppurating  sores  on  the  teats,  with  inflammation  or 
other  disease  of  the  udder,  constipation  or  diarrhoea. 
Moreover,  it  should  not  be  used  from  cows  that  are  being 
treated  with  medicines  that  have  a  strong  odor  (volatile 
oils,  ether,  asafcetida  and  the  like),  with  alkaloids  or 
potent  glycosides,  with  preparations  of  iodine,  arsenic, 
mercury,  antimony  or  lead. 

A  very  proper  requirement  is  that  milk  from  coivs 
that  have  recently  calved  is  not  to  be  mixed  ivith  the  rest 
of  the  milk,  for  the  beast  milk  (colostrum)  differs 
greatly  in  composition  from  normal  milk  and  may  have 
a  harmful  effect  on  small  children.  For  6  to  8  days 
after  calving,  the  milk  should  not  be  mixed  with  the 
other  milk.  Also,  milk  from  coivs  approaching  the 
end  of  the  period  of  gestation  and  ivhich  are  only 
giving  a  little  milk,  should  not  be  mixed  with  that 
intended  for  sale,  because  it  is  often  quite  alkaline  and 
may  differ  a  good  deal  in  its  composition  from  normal 
milk. 

The  complete  observance  of  these  requirements  is, 
evidently,  very  difficult  to  control.  In  part,  one  must 
rely  on  the  honesty  of  the  owner,  who  should  be  held 
responsible  for  failure  to  comply  with  the  legal  require- 
ments. When  a  dairyman  is  under  contract  to  furnish 
milk  to  a  company  having  its  own  conditions  and  regula- 
tions, he  may  be  held  accountable  for  failure  to  fulfil 
the  obligations  he  has  undertaken.  In  general,  it  can  be 


REGULATION  OF  PRODUCTION          171 

said  that  the  observance  of  the  conditions  that  are  out- 
lined above,  as  well  as  those  that  will  be  mentioned  later, 
can  be  expected  only  when  the  dairy  farm  is  under  the 
inspection  of  a  veterinarian  who  is  entirely  independent 
of  the  owner. 

Therefore,  when  it  is  possible,  one  should  endeavor 
strongly  to  arrange  for  such  veterinary  supervision. 
Naturally,  it  is  of  some  advantage  to  make  inspections 
now  and  then,  at  irregular  times,  but  if  the  control  is  to 
be  really  effective,  the  visits  must  take  place  frequently, 
and  with  some  degree  of  regularity.  Preferably,  the 
visits  should  not  be  more  than  fourteen  days  apart  be- 
cause, in  that  time,  tuberculosis  may  attain  such  develop- 
ment that  bacilli  may  be  excreted  with  the  milk,  and  dis- 
eases of  the  udder  often  develop  acutely  and  follow  a 
short  and  rapid  course,  thus  making  frequent  examina- 
tions necessary.  Only  in  cases  in  which  the  milk  is  sub- 
jected to  a  really  safe  process  of  pasteurization  before  it 
is  sold,  should  a  less  frequent  inspection  be  considered 
sufficient. 

[This  amount  of  supervision,  a  visit  to  each  produc- 
ing farm  ever}  two  weeks,  is  not  attainable  with  relation 
to  the  milk  supply  of  the  large  cities  of  the  United 
States,  nor  is  it  to  be  regarded,  in  the  present  provi- 
sional state  of  the  sanitary  development  of  the  country, 
as  necessary.  That  producing  farms  should  be  under 
some  supervision,  all  agree.  The  amount  of  supervision 
that  is  necessary  varies  with  the  conditions.  If  a  given 
herd  is  known  to  be  infected  with  tuberculosis  and 
infested  with  other  diseases,  if  the  premises  are  bad  and 
the  owner  careless,  then  frequent  inspections  should  be 
made  until  there  is  decided  improvement;  on  the  other 
hand,  if  a  certain  herd  is  known  to  be  clear  of  tuber- 
culosis, calf  cholera,  infectious  gargets,  etc.,  if  the  prem- 
ises are  good  and  well  kept  and  the  owner  intelligent  and 


172  MILK  HYGIENE 

careful,  longer  intervals  may  safely  be  permitted  to 
elapse  between  visits.  After  an  inspector  lias  gone  over 
his  ground  and  lias  become  acquainted  with  local  condi- 
tions, and  the  individuals,  the  question  of  frequency  of 
visits  should  be  left  to  a  larger  extent  to  him. 

The  number  of  inspectors  required  is  of  course  in 
direct  proportion  to  the  frequency  of  inspections.  If  a 
single  inspector  could  visit  all  of  the  dairy  farms  sup- 
plying a  given  city  in  one  year,  about  twelve  inspectors 
would  be  required  to  visit  these  farms  each  month.  It 
is  estimated  that  the  number  of  inspectors  that  would 
be  required  to  carry  out  an  adequate  system  of  dairy 
farm  inspection  for  the  city  of  Philadelphia  is  about  20. 
About  60  to  80  country  inspectors  would  be  required 
for  the  city  of  New  York.  L.  P.] 

For  herds  supplying  "  nursery  milk  "  or  "  infants' 
milk/'  decidedly  rigid  requirements  must  be  made  be- 
cause, so  far  as  possible,  this  milk  must  be  so  produced 
that  it  can  be  used  in  its  raw  state  by  children  and 
invalids  without  any  danger  whatever. 

Therefore,  dealers  should  not  be  permitted  to  sell 
milk  under  these  names  if  the  herds  are  not  under  the 
inspection  of  a  public  veterinary  officer ;  and  the  inspec- 
tions should  take  place  at  least  every  fourteen  days, 
preferably  every  week.  It  must  be  required  that ' i  nurs- 
ery milk  "  shall  come  only  from  herds  absolutely  free 
from  tuberculosis  (a.ev1ierds  that  are  tested  with  tuber- 
culin at  least  once  every  year,  and  to  which  only  abso- 
lutely healthy  animals  are  allowed  to  be  added),  be- 
cause the  diagnosis  of  some  dangerous  forms  of  tuber- 
culosis is  often  very  difficult  and,  in  the  earlier  stages, 
even  impossible,  and  because  it  has  been  proven  impossi- 
ble to  prevent  the  occurrence  of  the  dangerous  forms 
merely  by  the  removal  of  animals  in  which  tuberculosis 
is  clinically  apparent.  Besides,  the  definite  requirement 


REGULATION  OF  PRODUCTION          173 

must  be  made  that  the  delivery  of  milk  must  cease  in- 
stantly if  numerous  cases  of  septic  enteritis  or  strepto- 
coccus mastitis  appear  and  also  if  ' '  calf  cholera  ' '  occurs 
malignantly  or  endemically. 

Moreover,  the  prompt  removal  from  the  herd  is  de- 
sired of  every  animal  that  has  fever,  or  any  kind  of 
infectious  disease.  It  is  the  duty  of  the  owner  himself 
to  discontinue  the  delivery  of  the  milk  and  to  undertake 
the  necessary  isolation,  when  occasion  may  arise  be- 
tween the  visits  of  the  veterinarian,  and  he  should  call 
the  veterinarian  as  soon  as  any  suspicious  disease  may 
appear. 

These  .requirements  are  already  enforced  by  private 
companies  and  so  there  can  be  no  question  as  to  whether 
it  is  possible  to  carry  them  into  effect  but,  up  to  the  pres- 
ent time,  they  are  enforced  by  the  public  in  only  a  few 
cities. 

b.  Feeding  the  herd.  As  has  already  been  stated, 
it  is  now  the  belief  that  the  composition  of  the  milk  does 
not  depend  in  any  material  degree  on  the  composition 
of  the  food,  and  that  injurious  substances  are  not  ex- 
creted through  the  udder  to  the  extent  that  was  formerly 
supposed.  Therefore,  one  is  not  justified  in  forbidding 
the  use  of  such  a  number  of  foods  as  has  been  done  and 
is  still  done  by  some  large  cities.  Only  such  foods 
should  be  prohibited  as  are  decomposed  (mouldy,  putrid 
or  fermenting),  or  materials  containing  great  numbers 
of  resistant  bacteria  of  fermentation  (creamery  refuse, 
frozen  forage,  the  offal  of  root  crops,  etc.),  or  excessive 
quantities  of  unnatural  food  materials  (the  refuse  of 
some  manufactories,  distillers'  slops,  malt,  molasses 
etc.),  and  strongly  smelling  vegetable  matter  (turnip 
tops,  cabbage,  green  forage  containing  poisonous  plants, 
etc.).  The  use  of  other  food  stuffs  should  be  forbidden 
in  such  quantities  as  are  injurious  to  the  cow  (turnips 


174  MILK  HYGIENE 

causing  diarrhoea,  concentrated  feed  causing  indigestion, 
poisoning  by  cotton-seed  and  nut-cake,  etc.). 

It  has  been  required  in  some  cases  that  cows  supply- 
ing "  nursery  milk  "  shall  be  fed  only  upon  dried  fod- 
der, and  the  use  of  oil  meals  has  been  restricted.  By 
this  means,  milk  has  been  obtained  which  is  good  and 
uniform,  but  it  is  so  very  expensive  that  its  use  is  re- 
stricted. Our  present  knowledge  of  the  effect  of  food 
upon  milk  does  not  sustain  this  requirement.  But,  it 
should  be  observed,  the  stable  and  cows  can  be  kept  clean 
much  more  easily  if  the  cows  are  fed  exclusively  upon 
dry  foods  than  when  they  are  fed  in  part  upon  turnips  or 
other  green  food.  Therefore,  if  this  one-sided  method 
of  feeding  is  not  demanded,  great  emphasis  must  be 
placed  on  cleanliness  with  respect  to  herds  supplying 
nursery  milk.  It  is  not  inappropriate,  however,  to  make 
some  extra  requirements  in  regard  to  feeding  cows  pro- 
ducing nursery  milk.  For  example,  food  stuffs,  such  as 
distillers'  slops,  malt  and  molasses,  as  well  as  all  fodder 
which,  fed  in  large  quantities,  may  be  injurious  to  cows, 
should  not  be  used  (buckwheat,  lupine,  mustard,  rape, 
cakes  mixed  with  mustard,  cotton-seed  meal,  nut-cakes, 
potatoes,  etc.).  Of  course  it  is  difficult  to  prove  that  a 
ration  containing  a  small  quantity  of  these  materials 
would  impart  injurious  properties  to  the  milk ;  but  it  is 
safest,  when  it  concerns  milk  for  small  children,  to  avoid 
any  possible  danger  connected  with  the  use  of  such 
foods;  the  more  so,  as  this  prohibition  would  have 
no  influence  at  all  upon  the  cost  of  production  of  the 
milk.  Nor  should  one  be  allowed  to  give  so  great  a 
quantity  of  turnips  or  green  fodder  to  cows  that  are 
stabled  that  they  suffer  from  diarrhoea,  even  to  a  slight 
degree. 

[There  has  been  much  discussion  and,  in  the  past, 
much  difference  of  opinion,  as  to  the  propriety  of  using 


REGULATION  OF  PRODUCTION          175 

silage  as  a  food  for  milch  cows,  and  especially  as  food 
for  cows  producing  nursery  or  certified  milk. 

The  building  of  silos  and  the  ensiloing  of  crops  are 
new  procedures  in  America,  as  elsewhere,  and  methods 
both  of  construction  and  filling  have  undergone  rapid 
development.  Only  a  few  years  ago,  when  square, 
poorly  built  silos  were  used,  some  of  them  built  as  pits, 
below  ground,  and  before  silage  cutters  and  elevators 
had  been  developed,  and  when  it  was  the  practice  in 
some  cases  to  ensilo  green  maize  stalks  without  cutting, 
and  in  bundles,  there  was  much  decomposed,  putrid  and 
mouldy  silage,  which  had  a  very  offensive  odor  and 
which  was  decidedly  objectionable  as  food  for  dairy 
cows  or,  indeed,  for  any  animals. 

In  these  days,  however,  silos  are  better  made  and 
better  filled;  they  are  usually  round  or  octagonal,  thus 
facilitating  even  filling  and  settling,  machinery  for  cut- 
ting has  been  perfected,  so  that  the  silage  is  divided 
into  short  lengths  of  from  one-half  to  one  inch,  and 
Indian  corn,  the  chief  silage  crop,  is  no  longer  used  in 
the  soft,  immature  state,  but  is  permitted  to  come  al- 
most to  maturity.  Putrefaction  does  not  occur  in  prop- 
erly handled  silage.  The  fermentation  that  takes  place 
is  caused  partly  by  bacteria  and  partly  by  enzymes  in 
the  maize  plant.  Good  silage  is  a  wholesome,  nutritious 
food  that  is  appetizing  and  comparatively  easy  of  di- 
gestion. 

Silage  is  fed  to  cows  on  nearly,  if  not  quite,  all  of 
the  large  farms  in  America  devoted  to  the  production  of 
certified  and  nursery  milk.  It  is  not  known  to  be  subject 
to  any  objection  other  than  if  fed  in  too  large  quantity 
it  produces  an  undesirable  degree  of  laxativeness,  and 
if  fed  just  before  or  during  milking,  if  it  is  not  first  class, 
the  odor  of  the  silage  may  be  eliminated  with  or  ab- 
sorbed by  the  milk.  This  is  avoided  by  feeding  it  after 


176  MILK  HYGIENE 

milking  and  by  not  allowing  the  residues  to  accumulate 
in  or  about  the  stable. 

Frasier41  has  shown  by  some  tests  made  with  milk 
from  cows  fed  silage  of  good  quality  that  no  objection- 
able flavor  or  odor  was  imparted  to  the  milk  either  when 
the  silage  was  fed  before,  during,  or  after  milking.  In- 
deed, in  372  tests  made,  silage  milk  was  preferred  in 
233,  or  60  per  cent.  L.  P.] 

A  further  demand  in  reference  to  herds  supplying 
nursery  milk  should  be  established — that  frequent  and 
sudden  changes  in  food  should  be  forbidden,  as  the  com- 
position of  the  milk  immediately  after  such  a  change  is 
often  materially  altered,  and  it  is  more  probable  that 
when  the  udder  is  "  surprised'  by  such  a  sudden 
change  the  secretory  function  is  thrown  out  of  equilib- 
rium and  abnormal,  and  possibly  injurious,  substances 
are  secreted  with  the  milk. 

c.  Cleanliness  in  the  stable  and  during  milking.  In 
order  to  guard,  so  far  as  possible,  during  milking, 
against  pollution  with  dirt  and,  at  the  same  time,  with 
bacteria,  the  most  thorough  cleanliness  of  the  cows  and 
the  stable,  and  care  on  the  part  of  the  milkers,  is  to  be 
desired.  However,  it  is  very  difficult  to  establish  detailed 
regulations  in  this  respect,  and  no  less  difficult  to  en- 
force them.  We  usually  find  that  the  regulations  under 
this  heading  are  confined  to  the  concisely  stated  orders 
that  cows  and  stables  must  be  kept  clean ;  that,  at  milk- 
ing, the  greatest  possible  cleanliness  must  be  observed 
and  that,  just  before  milking,  the  udder  and  teats  are  to 
be  washed. 

However,  where  the  conditions  permit  the  establish- 
ment of  more  detailed  regulations,  as  in  the  larger  milk 

41  Wilber  J.  Frasier,  Bulletin  No.  101,  Agricultural  Experiment 
Station,  University  of  Illinois,  Urbana,  1905. 


REGULATION  OF  PRODUCTION          177 

companies,  which  are  under  private  control,  this  should 
be  done.  In  this  connection,  the  following  regulations 
which,  first,  the  Copenhagen  Milk  Supply  Company  and, 
afterward,  other  companies  in  Copenhagen,  have  fur- 
nished to  their  producers  stand  as  an  example  to  be 
imitated : 

1.  The  stable  must  be  so  built  that  the  urine  has  an 
unobstructed  exit  and  the  floor  must  be  of  such  nature 
that  it  may  easily  be  kept  clean.    The  cows  must  be  well 
bedded  and,  for  this  purpose,  no  spoiled  or  rotten  straw 
or  hay  can  be  used,  nor  straw  or  hay  that  has  previously 
been  used  for  packing.    The  stable  must  be  kept  as  clean 
as  possible.    In  the  morning,  the  manure  must  not  be 
removed  until  after  milking;  in  the  afternoon,  at  least 
one  hour  should  pass  after  mucking  out  before  milking. 
After  cleaning  the  stable,  it  should  be  thoroughly  aired, 
unless  the  ventilating  system  is  particularly  good,  so  as 
to  render  this  unnecessary. 

2.  In  order  to  prevent  the  hind  quarters  of  the  cow 
from  becoming  too  dirty,  the  hair  of  the  tail,  on  the 
udder,  the  flanks  and  on  the  outer  side  and  the  rear  of 
the  thighs  should  be  clipped  before  the  cow  is  stabled  in 
the  fall.    Besides  this,  the  cow  should  be  cleaned  with  a 
curry  comb  and  brushed  every  day.    Definite  and  more 
stringent  regulations  concerning  the  cleanliness  of  the 
stable  and  the  cows  should  be  made  in  summer,  if  they 
are  fed  in  the  stable,  and  in  winter  if  green  (laxative), 
fodder  is  used. 

3.  When  the  cows  are  kept  in  the  stable,  their  teats 
are  to  be  washed  with  clean  water  and  dried  with  a  clean 
cloth.    If  the  udder  is  dirty,  this,  also,  must  be  washed 
and  dried.     If  the  cows  are  milked  in  pasture,  this 
cleansing  cannot  be  done  so  satisfactorily   [and  there 
is  less  occasion  for  it],  so  it  is  usually  best  to  confine 
the  washing  of  the  teats  and  udder  to  such  of  the  cows 

12 


178  MILK  HYGIENE 

as  are  apparently  soiled  with  manure  or  earth.  If  there 
are  sores  upon  the  teats  these  must  be  carefully  washed 
off.  Instead  of  washing,  one  may  rub  the  udder  with  a 
dry  cloth  or  brush  it  and  then  rub  in  a  little  neutral  fat 
[as  vaseline].42 

4.  The  milkers  must  have  a  special  dress  to  be  used 
only  during  milking,  and  this  must  be  washed  as  often 
as  necessary.     The  milkers  must  wash  their  hands  be- 
fore milking,  and  during  milking  they  must  have  plenty 
of  clean  water  and  clean  cloths  at  hand  with  which  to 
wash  not  only  the  teats  but  also  their  own  hands,  as 
often  as  is  necessary. 

5.  Milk  pails,  milk  strainers  and  milk  cans  must  be 
carefully  cleaned  in  the  dairy  house.    If  it  be  necessary 
to  rinse  out  the  pails  or  strainers  when  milking  in  the 
pasture,  only  clean  water  which  has  been  carried  to  the 
place  must  be  used  and  not  that  from  a  reservoir  in  the 
pasture. 

d.  The  health  of  the  attendants.  A  very  important 
point  in  milk  hygiene  is  the  condition  of  health  among 
the  workers  in  the  dairy  and  of  the  milkers  and,  indeed, 
among  all  persons  who  are  connected  with  milk  produc- 
tion. As  has  already  been  emphasized,  there  are  a  num- 
ber of  infectious  diseases  of  man  which  can  easily  be 
transmitted  through  milk  and  which  have  appeared  in 
many  instances  as  extended  "  milk  epidemics. "  Fre- 
quent inspection  by  a  physician  of  all  persons  connected 

42  [This  reference  to  milking  cows  at  pasture,  which  has  now 
become  unusual  in  most  parts  of  America,  is  explained  by  the  Danish 
custom  of  keeping  cows  tethered  out  of  doors  the  entire  summer. 
During  this  season,  the  cows  are  allowed  to  graze  on  grass  and 
especially  planted  forage  crops,  which  are  harvested  by  the  cows 
without  waste,  as  the  tether  pin  to  which  the  tie  rope  is  attached 
is  moved  but  a  few  feet  at  a  time  and  is  not  moved  again  until  the 
forage  within  reach  has  been  consumed.  Water  is  carried  to  the 
cows  in  tanks  on  wagons.  L.  P.] 


REGULATION  OF  PRODUCTION          179 

with  the  business  is  scarcely  feasible,  both  because  it 
would  be  an  expensive  procedure  and  because,  in  most 
cases,  it  would  meet  with  great  opposition  and  tend  to 
increase  labor  difficulties. 

But  the  following  regulations  are  regarded  as  neces- 
sary and  they  should  be  incorporated  in  public  ordi- 
nances : 

The  sale  of  milk  shall  cease  immediately  if  typhoid 
fever,  scarlet  fever,  diphtheria,  or  other  malignant  in- 
fectious disease  breaks  out  among  people  living  in  the 
farmstead ; 43  the  sale  shall  not  be  resumed  until  a  physi- 
cian 's  certificate  has  been  received  showing  that  all  dan- 
ger of  infection  is  over.44 

Care  must  be  taken  that  the  milk  does  not  come  in 
contact  in  any  way  with  persons  in  whose  household  one 
of  the  above-mentioned  diseases  exists,  nor  those  who 
have  discharging  sores  or  skin  diseases  of  the  arms, 
hands  or  face. 

In  addition,  the  local  authorities  should  have  the 
right  to  forbid  the  sale  of  milk  if  this  is  known,  or  be- 
lieved, to  be  the  cause  of  an  epidemic,  even  though  no 
source  of  infection  be  proven  on  the  farms  in  question. 

Several  of  the  large  milk  companies  of  Copenhagen 
have  established  even  more  rigid  regulations  in  regard 
to  the  health  of  the  personnel  and  they  insure  the  en- 
forcement of  these  rules  by  allowing  the  producer  full 
value  for  his  milk,  when  he  holds  it  back  on  account  of 
the  occurrence  of  disease.  The  value  of  such  a  provision 
is  obvious. 

e.  The  water  supply.     Since  typhoid  bacteria    (and 

43  [The  farmer's  residence  and  the  cow  stable  adjoin,  so  that  they 
are,  practically,  parts  of  the  same  building,  on  most  of  the  small 
farms  of  Denmark.] 

44  [The  danger  of  infection  from  persons  recovering  from  typhoid 
fever  and  diphtheria  continues  for  a  long  time.] 


180  MILK  HYGIENE 

other  pathogenic  bacteria)  may  gain  access  to  milk 
through  water  used  to  wash  the  milk  vessels,  care  must 
be  taken  that  pure  water  be  provided  on  the  farms  from 
which  market  milk  is  sold,  and  that  polluted  or  infected 
water  is  not  used  for  cleansing  the  dairy  utensils,  nor 
the  udder,  nor  shall  it  be  used  for  the  cows.  [Contam- 
inated water  has  also  done  harm  when  used  for  cooling 
milk  and  it  is  believed  to  have  led  to  the  infection  of 
milk,  indirectly,  through  the  soiling  of  the  skin  of  the 
cow,  as  when  wading  through  a  foul  stream.  L.  P.] 

/.  The  care  of  the  milk.  Immediately  after  milking 
each  cow,  the  milk  must  be  run  through  a  fine  metal 
strainer  into  a  container.  The  strainer  holds  back  only 
the  larger  pieces  of  dirt  and  some  of  these  are  dissolved 
by  the  continuous  pouring  of  the  milk,  and  bacteria  are 
washed  through,  so  it  is  advisable,  so  far  as  possible,  to 
prevent  the  dirt  that  has  been  removed  from  coming  into 
contact  with  the  milk  that  is  to  follow.  But  it  cannot  be 
said  that  a  strainer  has  yet  been  made  that  solves  this 
problem  in  a  satisfactory  way;  therefore  one  must  get 
along  by  frequently  cleansing  the  strainer  from  the  par- 
ticles of  dirt.  Of  course,  it  is  very  difficult  to  insure  the 
observance  of  such  a  stipulation.  Sufficiently  rigid  re- 
quirements in  regard  to  the  cleanliness  of  the  milk  sold 
and  the  seizure  of  impure  milk,  followed,  perhaps,  by  the 
imposition  of  a  fine  would  aid  in  enforcing  the  regula- 
tion. 

After  the  milk  is  drawn,  it  must  be  carried  to  a  place 
prepared  for  this  use  and  which  must  be  used  for  no 
other  purpose.  This  room  must  be  well  ventilated,  clean 
and  have  an  impervious  floor. 

The  milk  must  be  cooled  as  soon  as  possible  by  pass- 
ing it  over  a  cooler  or  by  putting  the  cans  into  tanks 
containing  ice  water.  If  it  is  nursery  milk,  the  cooling 
must  be  very  carefully  done,  so  that  the  temperature 


REGULATION  OF  PRODUCTION          181 

may  not  exceed  10°  C.  (50°  F.).  Milk  should  be  kept 
chilled  until  it  is  ready  to  be  shipped  and  then  it  must  be 
guarded  carefully  against  high  temperature  by  protect- 
ing it  from  the  sun,  transportation  by  night,  etc. 

If  the  transportation  of  milk  requires  a  long  time,  it 
must  be  cooled  to  a  low  point,  and,  while  it  is  not  well  to 
allow  the  whole  quantity  to  freeze,  in  recent  years  a 
partly  frozen  milk  (the  outside  layer  frozen  in  the  cans) 
or  the  addition  of  frozen  milk  to  the  other  milk  have 
been  successfully  used. 

[Milk  shipped  long  distances  in  America  is  sent  in 
refrigerator  cars.  Some  milk  is  on  the  railroad  10  hours 
before  it  reaches  market.  Milk  shipped  short  distances 
is  usually  not  sent  in  refrigerator  cars  because,  on  the 
short  runs,  the  cars  have  to  be  opened  so  often  at  local 
stations  that  there  would  be  a  great  consumption  of  ice. 
If  such  milk  is  thoroughly  chilled  by  the  use  of  ice  before 
it  is  shipped,  it  usually  arrives  in  good  condition;  but 
if  it  is  cooled  only  by  the  use  of  well  or  spring  water  it 
is  an  uncertain  commodity  in  the  hottest  weather.  Bot- 
tled milk  is  shipped  in  wooden  boxes  with  broken  ice 
packed  around  the  bottles. 

Helm 45  has  proposed  that  milk  shall  be  shipped  in 
square,  instead  of  round,  cans,  so  that  they  may  be 
packed  more  closely  and  thus  make  a  solid  block,  of 
low  temperature,  which  may  be  covered  over  if  neces- 
sary, and  which  will  remain  cold  much  longer  than  a 
loose  collection  of  round  cans,  between  which  the 
warm  air  may  freely  circulate.  This  style  of  can  is 
shown  in  figure  14.  L.  P.] 

Only  well-tinned  metal  cans  which  are  easily  cleaned 
should  be  used  for  keeping  milk  (Fig.  13) ;  these  should 
be  closed  and  sealed  when  transported  by  rail  or  boat. 

45  Wilhelm  Helm,  Die  Milchbehandlung,  Liepzig,  1903. 


182 


MILK  HYGIENE 


II.    REGULATIONS    CONCERNING    THE    SALE 
AND    DELIVERY    OF    MILK 

Just  as  supervision  is  necessary  of  the  herds  which 
produce  the  milk,  and  in  regard  to  the  care  of  milk  at 
its  source,  so  also  is  supervision  necessary  after  it  comes 
into  the  hands  of  the  wholesale  and  retail  dealers.  This 
supervision  is  much  easier  to  carry  out  than  that  with 
relation  to  production. 

The  regulations  governing  sale  and  delivery  must 
embrace  not  only  the  methods  of  handling  the  milk  and 


FIG.  13. 


FIG.  14. 


Danish  milk-cans. 


Helm's  milk-cans. 


the  health  of  the  attendants,  but  there  should  also  be 
rules  concerning  the  place  in  which  the  milk  is  sold,  the 
manner  of  selling  it  and  the  labelling  of  the  goods. 

a.  Preparing  the  milk  for  delivery.  Although  small 
concerns  subject  the  milk  to  no  especial  treatment  from 
the  time  it  is  received  until  it  is  sold,  this  is  not  the  case 
with  the  large  companies.  These  have  considerable 
work  to  perform  in  the  handling  of  milk  and  its  delivery 
to  customers.  The  milk  [under  the  Danish  system]  is 
received  from  the  stations  in  a  more  or  less  cool  condi- 


REGULATION  OF  SALE  183 

tion  and  the  cans  are  put  into  ice  water  in  order  to  chill 
the  milk  sufficiently.  It  is  then  poured  into  a  tank  and 
mixed,  thus  making  its  composition  uniform.  Then  fol- 
lows a  process  of  cleansing,  wherein  the  milk  is  either 
passed  through  a  centrifuge,  so  constructed  that  the 
cream  and  the  milk  are  not  separated,  but  only  particles 
of  dirt  are  thrown  out,  or  it  is  passed  through  a  filtering 
apparatus  which  holds  back  some  of  these  particles.  A 
gravel  filter  is  frequently  used  for  filtering.  This  is  a 
tank  which  is  filled  with  layers  of  gravel  of  different 
degrees  of  fineness,  through  which  the  milk  is  slowly 
forced.  The  gravel  is  cleansed  daily  by  washing 
and  roasting.  Only  the  particles  of  dirt  are  removed 
by  this  process;  the  number  of  bacteria  is  not  appre- 
ciably reduced.  A  filter  made  of  numerous  layers  of  fine 
linen,  tightly  stretched,  has  been  used  successfully  in- 
stead of  the  gravel  filter.  The  cloth  part  is  renewed 
after  each  use.  This  method  has,  among  others,  the  ad- 
vantage that  the  filtering  may  take  place  directly  into 
the  can  from  which  the  milk  is  drawn  off  for  sale,  or  the 
apparatus  may  be  so  arranged  that  while  the  milk  is 
being  filtered  and  run  off,  it  is  at  the  same  time  cooled. 

The  "  clarified  "  milk  is  put  into  metal  cans  or  glass 
bottles  in  which  it  is  to  be  sold.  This  filling  is  sometimes 
done  automatically,  so  that  incorrect  measuring  is  not 
possible,  and  sometimes  by  means  of  a  machine  similar 
in  construction  to  those  used  in  filling  beer  bottles. 

If  the  milk  is  to  be  pasteurized,  it  is  first  filtered,  then 
run  through  the  pasteurizer  and  over  the  cooler,  into 
the  delivery  can;  or  it  is  placed  in  the  clean  bottles  or 
cans  that  go  into  the  pasteurizer  or  sterilizer  (see  page 
139). 

The  public  will  scarcely  require  ordinances  contain- 
ing exactly  detailed  regulations  in  regard  to  these  differ- 
ent processes.  Generally  it  is  required  only  that  the 


184  MILK  HYGIENE 

vessels  and  apparatus  used  shall  be  entirely  clean,  that 
the  milk  be  handled  with  the  greatest  cleanliness  and  be 
kept  in  well-tinned  metal  cans  or  in  glass  or  earthenware 
vessels  with  perfect  glazing,  containing  no  lead,  and  that 
all  vessels  shall  be  so  constructed  that  they  will  not  be 
difficult  to  clean. 

Special  regulations  should  be  established  for  the  pas- 
teurisation of  milk.  If  the  heating  is  of  short  duration, 
it  is  desirable  that  the  milk  be  heated  to  80°  C.  (176°  F.) 
and  cooled  immediately  afterward.  The  following  re- 
quirements should  be  established  for  heating  at  a  lower 
temperature:  Milk  should  be  raised  to  a  temperature 
of  65°  to  70°  C.  (149°  to  158°  F.)  and  held  there  for  one- 
fourth  hour  or  it  should  be  kept  for  one-half  hour  at  a 
temperature  of  60°  to  65°  C.  (140°  to  149°  F.).  The 
pasteurizer  should  be  known  to  act  accurately  enough 
to  attain  the  required  temperature  with  certainty. 

b.  The  places  for  keeping  and  selling  milk.  The  places 
in  which  milk  is  handled  must  be  light,  airy  and  easy  to 
keep  clean;  therefore,  they  must  be  provided  with  an 
impervious  floor  and  a  good  drain,  and  good,  pure  water 
must  be  easily  accessible. 

The  salesplaces  must  likewise  be  bright,  airy  and 
clean  and,  in  addition,  there  are  a  number  of  special 
requirements.  Milk  should  not  be  allowed  to  be  sold  in 
the  same  shop  with  other  goods,  with  the  exception  of 
certain  foods  (as  bread,  honey,  flour,  butter,  margarin 
and  eggs),  which  cannot,  either  by  their  odor  or  in  any 
other  way,  have  a  deleterious  influence  on  the  flavor  and 
the  keeping  quality  of  the  milk.  Conducting  a  laundry, 
or  a  similar  business,  in  the  same  place  in  which  milk  is 
kept  or  handled,  should  not  be  permitted.  Of  course, 
the  apartment  must  not  be  used  as  a  dwelling  or  a  sleep- 
ing room,  and  it  should  not  be  in  direct  communication 
with  sleeping  rooms.  If  the  place  used  for  keeping  and 


REGULATION  OF  SALE  185 

selling  milk  is  in  communication  with  living  rooms,  as 
happens  in  small  premises,  then  it  is  positively  neces- 
sary to  have  the  apartments  separated  by  a  thick  door, 
which  shall  be  kept  closed. 

c.  The  condition  of  health  of  the  attendants.     The  same 
rules  that  apply  to  attendants  in  the  places  of  production 
should  be  binding  upon  those  at  the  salesplaces.    How- 
ever, as  the  enforcement  of  these  rules  naturally  meets 
very  great  difficulties,  in  most  cities  action  has  been 
limited  to  making  the  regulation  and  then  punishing 
those  guilty  of  offences  that  are,  by  chance,  discovered. 

Several  large  concerns  (e.g.,  some  in  Copenhagen) 
have  voluntarily  enforced  strict  regulations  in  regard  to 
the  health  of  attendants.  In  order  to  be  sure  that  no 
suspicious  disease  among  them  or  in  their  households 
shall  escape  being  reported,  they  provide  free  medical 
services  and  also  pay  full  wages  to  every  employee 
who  is  temporarily  absent  from  his  work  on  account  of 
illness  in  his  family.  (Compare  regulations  governing 
the  producers  for  this  society,  page  178,  and  Appendix 
I,  page  241.) 

Moreover,  the  public  health  department  of  the  gov- 
ernment must  be  authorized — possibly  upon  the  pay- 
ment of  indemnity — to  close  milk  businesses  for  a  longer 
or  shorter  time,  which  are  known  to  spread  contagion, 
even  though  it  cannot  be  shown  just  where  the  infection 
comes  from.  This  authority  must  also  apply  to  milk 
shops,  when  cases  of  typhoid  fever,  scarlet  fever  or 
diphtheria  exist  among  people  who  work  with  the  milk. 
If  it  is  proven  that  the  infection  did  not  occur  in  the 
shop,  the  milk  and  the  cream  may  be  sold  after  steriliza- 
tion, if  care  is  taken  to  see  that  this  is  thoroughly  done. 
A  milk  shop  is  to  be  kept  closed  as  long  as  there  is  dan- 
ger that  it  may  distribute  infection. 

d.  Marking  and  packing  the  milk.     The  requirements 


186  MILK  HYGIENE 

in  respect  to  marking  niilk  for  sale  form  quite  an  impor- 
tant part  of  the  regulations  on  the  handling  of  milk,  be- 
cause these  have  a  very  important  bearing  on  the  pre- 
vention of  adulteration.  The  kinds  of  milk  and  milk 
products  which  are  of  importance  are  whole  milk,  ' l  half 
milk,"  skim  milk,  cream  and  buttermilk. 

Whole  milk  is  the  usual  name  for  normal  cow's  milk 
which  has  not  been  deprived  of  any  of  its  fat  or  other 
ingredients.  As  the  fat  content  of  milk  is  far  from  being 
uniform,  and  as  partial  skimming,  or  the  addition  of 
skimmed  milk,  is,  therefore,  not  easily  detected,  many 
attempts  are  made  to  deceive  by  these  falsifications.  In 
order  to  prevent  the  sale  of  milk  that  may  be  unadulter- 
ated but  which  is  too  poor  in  fats,  and  in  order  to  lessen 
the  number  of  adulterations,  a  minimum  content  of  fat 
and  solids  has  been  established  in  many  cities,  as  well  as 
the  limits  of  the  specific  gravity.  Milk  which  does  not 
contain  the  required  amount  of  fat  cannot  be  sold  as 
whole  milk;  if  it  is  so  sold  it  is  considered  adulterated. 

Eeinsch46  has  made  a  comparison  of  these  require- 
ments in  the  German  cities.  Among  63  ordinances,  60 
contain  such  a  minimum  limit  for  fat ;  37  of  these  place 
the  limit  at  2.7  per  cent,.  5  at  2.4  per  cent,  to  2.5  per 
cent.,  7  at  2.8  per  cent.,  9  at  3  per  cent,  and  only  2  have 
established  a  higher  minimum  at  3.2  per  cent,  to  3.3 
per  cent.  In  19  ordinances,  the  minimum  content  of 
solids  varies  between  10.5  per  cent,  and  12  per  cent.; 
most  require  11  per  cent,  to  11.5  per  cent.  Twenty- 
five  place  the  limits  of  specific  gravity;  10  of  these  as 
1.028  to  1.034,  8  as  1.029  to  1.033  and  5  as  1.029  to  1.034, 
while  a  single  one  provides  1.027  to  1.034. 

[The  German  standards  are  low  because  the  fat  con- 
tent of  the  milk  of  some  of  the  breeds  of  dairy  cows 

46  Die  gesetzhche  Regelung  des  Milchverkehrs  in  Deutschland, 
Hamburg,  1903. 


REGULATION  OF  SALE  187 

in  Germany  is  very  low.  It  would  be  quite  impracti- 
cable to  enforce  higher  standards  under  such  circum- 
stances. 

In  26  states  of  the  United  States  there  are  laws  estab- 
lishing milk  standards.47  The  limits  for  fat  are  from  3 
per  cent,  (in  one  state  only  is  the  limit  below  3  per  cent. ; 
in  Rhode  Island  it  is  2.5  per  cent.)  to  3.5  per  cent,  (in  one 
state,  Massachusetts,  for  half  the  year,  the  limit  is  3.7 
per  cent.).  For  total  solids,  the  limits  are  from  12  per 
cent,  (in  one  state  only  is  the  standard  lower:  Ohio, 
during  May  and  June,  it  is  11.5  per  cent.)  to  13  per 
cent. 

The  standards  for  cities  and  towns  vary  within  the 
same  limits ;  some  are  established  by  the  state  standard 
and  some  by  the  cities  themselves.  L.  P.] 

It  is  evident  from  the  above  requirements  that  it  is 
difficult  to  agree  on  percentages  and  standards  which 
may  be  considered  perfectly  just  and  reasonable.  If  the 
requirements  are  placed  too  high,  the  owners  of  a  num- 
ber of  herds  (especially  those  made  up  of  purchased 
cows)  soon  find  it  impossible  to  deliver  milk  in  the  cities ; 
if  the  requirements  are  placed  too  low,  the  object  of  reg- 
ulation is  attained  only  to  a  very  limited  extent.  There- 
fore, it  has  been  suggested  that  different  grades  of  whole 
milk  be  established.  Leipzig  and  Dresden  have  such 
a  provision,  under  which  only  milk  with  a  minimum  fat 
content  of  2.8  per  cent,  to  3  per  cent,  is  permitted  to  be 
sold  as  " whole  milk  I  quality/'  while  unadulterated 
cow's  milk  of  less  fat  content  can  be  sold  under  the 
name  "whole  milk  II  quality";  in  Leipzig,  however, 
this  can  be  marketed  only  with  the  designation  of  the 
fat  content.  Several  other  Saxon  cities  have  similar 

47  H.  E.  Alvord  and  R.  A.  Pearson,  The  Milk  Supply  of  200 
Cities  and  Towns,  U.  S.  Dept.  of  Agr.,  B.  A.  L,  Bulletin  No.  46, 
Washington,  1903. 


188  MILK  HYGIENE 

provisions,  under  which  milk  containing  less  than  2.8 
per  cent,  fat  can  be  sold  only  with  a  definite  statement 
of  the  fat  content. 

It  must  depend  upon  local  conditions  whether  such  a 
provision  is  desirable  or  not,  and  also  whether  it  is  re- 
garded as  wise  to  establish  a  minimum  fat  (and  solid) 
content,  and  at  what  point  these  should  be  placed. 

[Legal  standards  for  milk  are,  by -some,  objected  to 
on  two  grounds ;  first,  that  it  is  unfair  to  establish  a  mini- 
mum standard  so  high  that  it  will  exclude  the  milk 
from  some  cows,  and,  second,  that  if  the  standard  is 
low  it  will  encourage  dealers  to  dilute  rich  milk  to  a  point 
just  above  the  standard. 

As  to  the  first  objection,  it  does  not  appear  to  be  un- 
reasonable that  an  article  of  food  sold  as  milk  shall  be 
required  to  contain  a  certain  minimum  amount  of  nutri- 
ment. Entirely  aside  from  the  adulteration  of  milk, 
which  such  standards  are  established  to  check,  it  is  pos- 
sible to  select  and  develop  herds  of  cows  of  certain 
breeds  that  will  furnish  milk  of  very  low  fat  and  solids— 
not  fat  content.  What  has  occurred  in  this  direction 
is  shown  by  reports  on  the  weekly  analyses  of  the  milk 
of  a  herd  of  cows  at  Jaschkowitz,48  where  the  milk  ran 
down  to  2.47  per  cent,  fats  and  7.88  per  cent,  solids  not 
fat.  The  lowest  average  for  the  herd  for  a  month  was : 
fat,  2.60  per  cent. ;  solids  not  fat,  8.06  per  cent. ;  total 
solids,  10.66  per  cent.  The  official  records  of  Holstein 
cows  49  show  that  many  individuals  yield  milk  contain- 
ing less  than  3.0  per  cent,  of  fat,  and  some  as  little,  for 
a  time  at  least,  as  2.6  per  cent.  This  tendency  could, 
undoubtedly,  be  intensified  if  the  absence  of  milk  stand- 

48  Berieht  iiber  die  Tatigkeit  des  Milchwirtschaftlichen  Instituts 
zu  Proskau  fur  das  Jalir  1905-1906. 

49  C.  B.  Lane,  Record  of  Dairy  Cows  in  the  United  States,  U.  S. 
Dept.  of  Agr.,  B.  A.  I.,  Bulletin  No.  75,  Washington,  1905. 


REGULATION  OF  SALE  189 

ards  favored  it.  In  other  words,  the  milk  could  be  wa- 
tered through  the  cow.  The  tendency  among  breeders 
of  Netherland  cattle  in  America  (and  largely  on  account 
of  milk  standards)  is  to  increase  the  fat  content  of  their 
milk,  and  many  such  cows  yield  milk  containing  4  per 
cent,  to  4.5  per  cent.,  and,  exceptionally,  even  5  per 
cent,  of  fat. 

In  regard  to  the  second  objection,  the  dilution  of  rich 
milk  is  scarcely  more  likely  to  be  practiced  if  there  is  a 
minimum  standard  than  if  there  is  none,  and  it  can  be 
prevented  quite  as  effectively  by  law,  inspection  and 
penalty  with  a  minimum  standard,  as  without  one. 

All  of  the  existing  standards  in  the  United  States 
are  much  below  the  average  quality  of  the  milk  sold  in 
the  cities  to  which  the  standards  apply.  It  is  proposed 
by  Wing 50  that  no  special  standard  be  established,  but 
that  each  dealer  be  required  to  guarantee  his  own  stand- 
ard, and  that  he  be  held  responsible  if  his  milk  be  found 
below  this  guarantee.  Some  dealers  now  sell  bottled 
milk  of  different  grades,  containing  either  4  per  cent, 
or  5  per  cent,  of  fat,  but  all  of  it  is  above  the  minimum 
standard.  L.  P.] 

Special  rules  must  be  made  for  milk  sold  under  the 
name  "infants'  milk"  or  "nursery  milk,"  and  it  must 
be  required  that  this  shall  come  absolutely  from  herds 
that  are  under  constant  veterinary  inspection  and  whose 
condition  of  health  and  cleanliness  and  feed  are  gov- 
erned by  special  requirements  (see  page  174).  In 
a  number  of  German  ordinances,  in  addition  to  these  re- 
quirements, the  minimum  fat  content  is  placed  at  3.0  per 
cent.,  which  is  considered  fair.  [In  the  United  States 
"Certified  milk"  is  usually  required  to  contain  4  per 
cent,  fat.]  Another  regulation  which  is  justly  put  upon 

50  H.  H.  Wing,  Milk  and  its  Prodncts,  New  York  and  London, 
1899. 


190  MILK  HYGIENE 

the  dealer  in  nursery  milk  is  that  the  milk  shall  be  sold 
only  in  clear  glass  bottles  and  that  the  bottles  shall 
be  cleansed  or  sterilized  before  they  are  filled. 

It  should  be  required  that  milk  sold  as  "  controlled  " 
("certified"  or  "guaranteed")  shall  come  from  herds 
that  are  under  constant  and  competent  veterinary  in- 
spection. 

Half  skimmed  or  "  half  milk  "  is  milk  from  which 
a  part  of  the  fat  has  been  removed.  It  is  well  to  estab- 
lish a  minimum  fat  content  of  1  to  1.5  per  cent.,  as 
already  has  been  done  in  some  German  cities. 

[In  most  cities  in  America,  milk  that  is  below  the 
minimum  standard,  as  half  skimmed  milk  is,  can  be  sold 
legally  only  as  skimmed  milk.  There  is  no  grade  for 
milk  between  whole  milk  and  skimmed  milk.  The  desira- 
bility of  establishing  such  a  grade  may  well  receive  care- 
ful consideration.  The  same  end  could  be  gained  by  the 
adoption  of  Wing's  suggestion,  but  its  enforcement 
would  entail  administrative  difficulties.  L.  P.] 

[Skimmed  milk  is  milk  from  which  the  cream  has 
been  removed  by  hand  skimming  or  from  which  the  but- 
ter-fat has  been  extracted  by  means  of  a  centrifugal  sep- 
arator. The  former  kind  may  contain  from  0.5  per 
cent,  to  1.5  per  cent,  fat,  while  the  latter  rarely  con- 
tains more  than  0.3  per  cent,  fat  and  sometimes  as  little 
as  0.01  per  cent.  The  sale  of  skimmed  milk  is  wholly 
prohibited  in  some  American  cities,  as  in  New  York. 
This  prohibition  is  placed  on  account  of  the  great  in- 
clination on  the  part  of  some  dealers  to  sell  skimmed 
milk  as  whole  milk  and  the  difficulty  of  detecting  and 
preventing  this  practice.  It  is  possible,  however,  to 
secure  a  proper  observance  of  the  law  on  this  subject,  as 
is  proven  by  the  experience  of  cities  in  all  countries,  and 
it  would  be  far  better  for  the  rich  City  of  New  York  to 
employ  more  inspectors,  if  necessary,  to  prevent  fraud 


REGULATION  OF  SALE  191 

in  the  sale  of  skim  milk  than  to  deprive  the  poor  of 
this  wholesome,  nutritious  and  cheap  food. 

It  should  be  required  in  every  case  that  vessels  con- 
taining skim  milk  shall  be  permanently  and  conspicu- 
ously marked.  To  deliver  or  to  store  skimmed  milk  in  an 
unmarked  container  on  the  premises  or  wagon  of  a 
dealer  should  be  regarded  as  evidence  of  intent  to  de- 
fraud and  should  subject  the  violator  to  penalty. 

Skimmed  milk  should  contain  not  less  than  9.25  per 
cent,  of  milk  solids.  L.  P.] 

Cream,  for  the  production  of  which  the  same  sani- 
tary requirements  are  necessary  as  for  milk,  should  be 
sold  with  the  fat  content  designated,  if  there  is  no  local 
regulation  to  grade  it  or  establish  fat  percentages. 
[The  percentage  of  fat  in  cream  varies  from  8  per 
cent,  to  50  per  cent.,  or  more.  The  usual  quality,  as 
sold  in  the  market,  contains  about  15  per  cent,  to  20  per 
cent.  fat.  The  standard  for  cream,  as  established  by 
the  U.  S.  Department  of  Agriculture,  is  18  per  cent. 
Heavy,  rich  cream  contains  from  30  per  cent,  to  40 
per  cent.  fat.  L.  P.] 

[Buttermilk  requires  no  special  standard  except  that 
it  be  made  from  clean  milk,  and  in  a  cleanly  way.  It  is 
largely  used  as  a  summer  beverage  and,  as  typhoid 
bacilli  and  other  pathogenic  forms  will  live  in  it  for 
some  time,  it  is  important  that  it  be  protected  from  con- 
tamination. An  imitation  of  buttermilk  is  sometimes 
made  in  city  milk  shops  by  churning  sour  skimmed  milk. 
L.P.] 

Pasteurized  milk.  The  following  regulations  are 
proposed  for  milk  that  has  been  heated  and  that  is  to  be 
sold  as  i  i  pasteurized  ' ' :  Under  this  name,  and  without 
a  more  detailed  statement,  should  be  understood  milk 
that  has  been  heated  to  at  least  80°  C.  (176°  F.) ;  if  the 
milk  is  pasteurized  at  a  lower  temperature,  this  must  be 


192  MILK  HYGIENE 

distinctly  marked  upon  the  bottle  or  can,  and  the  milk 
must  not  be  permitted  to  go  upon  the  market  until  the 
method  has  received  official  sanction.  Sterilized  milk 
should  be  sold  only  with  a  statement  of  the  way  in  which 
sterilization  has  been  done,  and  not  until  after  the 
method  has  been  inspected  and  approved.  But  it  is  not 
enough  merely  to  establish  such  requirements ;  the  sani- 
tary officers  must  see  to  their  enforcement,  partly  by  vis- 
iting the  pasteurizing  and  sterilizing  establishments, 
partly  by  taking  samples  and  examining  the  milk  sold. 
Fortunately,  it  is  possible  to  determine  by  chemical 
means  whether  milk  has  been  heated  to  80°  C.  (176°  F.) 
or  not.  These  tests  are  based  on  an  observation  by 
Arnold  and  have  been  developed  by  Babcock,  Storch  and 
others.51  The  principles  are  the  following: 

Starch's  method:  5  c.c.  of  milk  are  poured  into  a -test  tube;  a 
drop  of  weak  solution  of  hydrogen  dioxide  (about  0.2  per  cent.), 
which  contains  about  0.1  per  cent,  sulphuric  acid,  is  added,  and  2 
drops  of  a  2  per  cent,  solution  of  paraphenylendiamin,  then  the 
fluid  is  shaken.  If  the  milk  or  the  cream  becomes,  at  once,  indigo 
blue,  or  the  whey  violet  or  reddish  brown,  then  this  has  not  been 
heated  or,  at  all  events,  it  has  not  been  heated  higher  than  78°  C. 
(172.5°  F.) ;  if  the  milk  becomes  a  light  bluish  gray  immediately  or 
in  the  course  of  half  a  minute,  then  it  has  been  heated  to  79°  to  80° 
C.  (174.2°  to  176°  F.).  If  the  color  remains  white,  the  milk  has  been 
heated  at  least  to  80°  C.  (176°  F.).  In  the  examination  of  sour  milk 
or  sour  buttermilk,  lime  water  must  be  added,  as  the  color  reaction  is 
not  shown  in  acid  solution. 

Arnold's  guaiac  method:  a  little  milk  is  poured  into  a  test  tube 
and  a  little  tincture  of  guaiac  is  added,  drop  by  drop.  If  the  milk 
has  not  been  heated  to  80°  C.  (176°  F.),  a  blue  zone  is  formed 
between  the  two  fluids;  heated  milk  gives  no  reaction,  but  remains 

51  Heating  milk  to  a  high  temperature  coagulates  the  albumin 
and  globulin  and  the  milk  loses  its  property  of  curdling  by  the 
action  of  rennet.  By  this  change  one  may  discover  that  it  has 
been  heated,  but  not  determine  whether  the  milk  has  been  heated 
to  80°  C.  (176°F.),  that  is,  if  it  has  been  pasteurized. 


REGULATION  OF  SALE  193 

white.  The  guaiac  tincture  should  not  be  used  perfectly  fresh  but 
should  have  stood  a  few  days  and  its  potency  have  been  determined. 
According-  to  the  observations  by  Glage,  the  guaiac-wood  tincture 
appears  to  be  more  reliable  than  the  harz  tincture.  Zink  recommends 
the  addition  of  a  few  drops  of  weak  solution  of  hydrogen  dioxide, 
as  this  causes  the  reaction  to  be  much  surer  and  sharper. 

Of  the  two  methods,  the  guaiac  method  is  preferable  in  that  the 
tincture  is  very  lasting  and  may  be  kept  a  year  without  becoming 
ineffective,  while  the  paraphenylendiamin  solution  must  be  renewed 
quite  often ;  on  the  other  hand,  the  guaiac  method  is,  perhaps,  hardly 
so  accurate  as  the  Storch  method. 

Other  substances  are  useful  as  reagents  in  combination  with 
hydrogen  dioxide,  as  solution  of  potassium  iodide  with  starch 
(Storch,  du  Roi,  Kohler  and  others)  and  ursol  (Utz)  ;  besides  these, 
a  methylene-blue-formalin  solution  (Schardinger)  has  been  suggested 
for  this  purpose. 

[  Storch 's  test  may  also  be  used  for  the  purpose  of 
detecting  the  adulteration  of  fresh  milk  with  diluted 
condensed  milk.  In  this  case  it  is  well  to  make  the  test 
comparative  by  running  a  parallel  sample  of  milk  known 
not  to  have  been  heated.  L.  P.] 

The  sale  of  milk  preparations  which  are  made  either 
by  using  foreign  additions  or  by  some  special  manipula- 
tion of  the  milk  should  be  permitted  only  when  the  milk 
has  been  produced  under  the  requirements  above  stated 
and  only  on  declaration  of  the  composition  of  the  prep- 
aration. 

Milk  containers.  In  case  the  milk  is  retailed  in 
containers,  there  should  be  some  stipulation  in 
regard  to  these.  Metal  cans  should  be  of  tinned  iron ; 
for  tinning,  no  tin  should  be  used  that  has  more  lead 
than  is  absolutely  necessary;  the  form  must  be  such 
that  they  can  be  easily  cleaned.  Bottles  are  to  be  made 
of  clear  glass  so  that  every  impurity  is  noticeable; 
their  form  must,  likewise,  make  satisfactory  cleansing 
possible. 

In  recent  years,  the  large  milk  companies  have  en- 
is 


194  MILK  HYGIENE 

deavored  in  their  own  interest,  as  well  as  in  that  of  the 
public,  to  provide  sealed  stoppers  or  covers  for  delivery 
bottles  and  cans,  which  more  surely  prevents  their  being 
opened  before  delivery  and  which  makes  it  impossible 
for  an  unscrupulous  person  to  fill  anew,  with  milk  or 
cream,  the  vessel  which,  from  accident  or  improper  rea- 
sons, was  partly  or  wholly  emptied.  With  metal  cans, 
this  security  is  most  easily  effected  by  the  use  of  a 
simple  lead  and  wire  seal,  applied  after  filling.  A  per- 
fectly reliable  closure  for  the  bottles,  on  the  other  hand, 
offers  some  difficulty,  because  it  is  so  expensive.  The 
accompanying  illustrations  show  some  of  the  methods 
used.  Fig.  15  shows  a  method  of  closing  which  corre- 
sponds to  that  used  on  mineral-water  bottles.  After 
closing,  a  label  is  pasted  over  the  top;  this  method  is 
somewhat  expensive  and  does  not  furnish  a  satisfactory 
guarantee  as  the  label  is  easily  loosened.  Fig.  17  shows 

FIG.  15. 


FIG.  17. 
FIG.  16. 


the  method  used  by  the  "  Trifolium  "  milk  company  in 
Copenhagen.  The  upper  part  of  the  neck  is  perforated, 
and  after  the  bottle  has  been  closed  by  the  insertion  of 
the  stopper,  a  wire  is  drawn  through  the  holes  and  se- 
cured with  a  lead  seal;  this  method  gives  efficient  pro- 
tection but  is  somewhat  expensive.  Fig.  16  shows  a 
method  used  during  recent  years  in  Germany,  which  is 
cheap  and  quite  satisfactory.  In  the  inside  of  the  neck 


REGULATION  OF  SALE  195 

there  is  a  small  groove;  after  the  bottle  is  filled,  it  is 
closed  with  a  paraffined  pulpboard  cap  which  is  pressed 
down  into  the  neck  of  the  bottle  by  means  of  a  stamp, 
with  its  edges  in  the  groove ;  at  the  same  time,  the  cap 
is  marked,  and  it  cannot  be  taken  out  without  being  torn. 
A  similar  cover,  a  pasteboard  cap  which  is  pressed  a 
little  way  into  the  bottle  (without  the  groove),  is  used  by 
many  milk  concerns,  but  this  gives  little  security,  as  the 
cap  can  easily  be  taken  out  and  a  new  one  substituted. 

[Paper  or  wood-pulp  discs  (sterilized)  used  as  stop- 
pers may  be  sealed  by  pouring  on  top  of  them  a  little 
melted  paraffine.  This  method  is  used  by  some  dairies 
that  produce  certified  milk.  The  customary  method, 
however,  among  the  best  dairymen,  is  to  cover  the  top 
of  the  bottle,  after  it  is  closed  with  the  usual  disc,  with 
a  cap  of  parchment  paper,  held  around  the  neck  of  the 
bottle  with  a  wire,  cord  or  rubber  band;  or  a  cap  of 
heavy  tin  foil  is  used,  which  is  pressed  down  around  the 
shoulder  at  the  mouth  of  the  bottle,  and  this  holds  its 
position  quite  well.  Both  of  these  methods  have  the  ad- 
vantage of  thoroughly  guarding  the  mouth  of  the  bottle 
and  the  disc  that  confines  the  milk.  The  lip  of  the  bottle, 
over  which  the  milk  must  be  poured,  is  prevented  from 
becoming  soiled.  These  methods,  however,  do  not  afford 
such  complete  protection  against  tampering  with  the 
contents  of  the  package  as  is  furnished  by  a  lead  seaL 
However,  if  the  box  in  which  the  bottles  of  milk  are 
shipped  from  the  farm  to  the  distributing  point,  or  to 
the  customer,  is  sealed  with  a  lead  seal,  as  is  done  by 
some  producers,  the  protection  is  sufficient. 

The  usual  practice  among  average  dairymen  is  to 
depend  on  unparaffined  and  unsterilized  wood-pulp  discs, 
upon  which  is  often  printed  the  name  of  the  dealer. 

Small  dealers  (and  some  large  ones  as  well)  some- 
times indulge  in  the  most  vicious  and  unsanitary  prac- 


196  MILK  HYGIENE 

tices  in  regard  to  bottling  milk.  They  pour  milk  into 
bottles  from  cans  in  their  wagons  or  hand  carts  on  the 
street,  exposing  it  to  dirt,  and,  worst  of  all,  they  some- 
times fill  bottles  that  have  not  been  cleaned,  or  that  have 
not  been  properly  cleansed.  Milkmen  have  been  known 
to  take  a  soiled  bottle  from  the  house  of  a  customer,  fill 
it  with  milk  on  a  dirty  wagon,  while  the  wind  is  blowing 
dust  about,  close  it  with  a  disc  taken  from  a  coat  pocket, 
perhaps  from  alongside  a  handkerchief,  and  then  deliver 
it  in  the  next  house.  It  is  not  surprising  that  it  has  been 
seriously  proposed  to  prohibit  the  use  of  milk  bottles. 
But  the  bottling  of  milk  marks  a  distinct  sanitary  ad- 
vance, where  it  is  carried  out  in  a  proper  manner.  It 
should  be  provided  by  public  regulation  that  milk  shall  be 
delivered  in  bottles  only  under  the  following  conditions : 

1.  Before  they  are  filled,  bottles  shall  be  washed  and 
sterilized,  or  they  shall  be  cleansed  by  the  use  of  some 
method  that  has  the  approval  of  the  sanitary  authorities. 

2.  Stoppers  for  the  bottles  shall  be  clean  (preferably 
sterilized)  and  shall  be  kept  only  in  sterile  packages  or 
in  a  clean  metal  or  glass  receptacle  provided  exclusively 
for  this  use. 

3.  Bottles  shall  be  filled  with  milk  only  in  a  clean 
room  provided  for  this  purpose,  and  they  shall  not  be 
removed  from  this  room  until  they  are  stoppered.  L.  P.] 

III.    PUBLIC  SUPERVISION  TO  PREVENT  ADULTERATION 

Just  as  many  foods  can  be  adulterated,  so  also  can 
milk  and  cream.  As  the  fat  is  the  most  valuable  ingredi- 
ent of  milk,  a  common  adulteration  consists  in  partial 
skimming,  or  in  the  addition  of  skimmed  milk  or  water ; 
less  frequently,  foreign  material  is  added  to  the  milk  in 
order  to  give  it  a  better  appearance.  It  can  be  only 
excessively  rarely  that  gross  adulterations  occur,  such 
as  the  one  reported  by  Sullivan,  wherein  a  sample  of 


PUBLIC  SUPERVISION  197 

"  milk  "  was  found  to  consist  of  a  mixture  of  water, 
white  pigment,  common  salt  and  a  little  skimmed  milk. 

There  is  no  general  rule  as  to  the  frequency  of  adul- 
teration. In  some  cities,  it  does  not  appear  to  be  partic- 
ularly frequent,  while  in  others  it  is  very  common. 

Besides  the  adulterations  found  upon  official  exam- 
inations of  the  market  milk  in  cities,  the  question  of 
fraud  sometimes  arises  in  connection  with  the  milk  deliv- 
ered to  creameries.  In  the  creameries,  it  is  customary 
to  use  some  quick  method  for  determining  the  approx- 
imate fat  content  of  the  milk  that  is  delivered  by  the 
various  patrons. 

In  the  official  control  of  milk  in  cities  two  provisional 
or  preliminary  tests  have  long  been  used  and  these  are 
still  depended  on  to  some  extent ;  they  consist  in  the  de- 
termination of  the  specific  gravity  and  in  a  test  of  the 
transparency.  Even  when  used  in  conjunction,  these 
tests  are  not  to  be  relied  upon  very  far,  but  they  can  be 
used,  if  with  sufficient  caution,  to  determine  whether  a 
more  thorough  examination  be  necessary.  If  it  is  de- 
cided that  a  laboratory  examination  is  required,  a  sam- 
ple should  be  taken  with  great  care,  and  sealed  and 
delivered  to  the  appropriate  expert  for  analysis. 

The  specific  gravity  of  cow's  milk  varies  between 
about  1.027  and  1.040  at  15°  C.  (60°  F.) ;  but  such  differ- 
ences are  to  be  found  only  in  the  milk  of  certain  indi- 
vidual cows.  The  specific  gravity  of  mixed-herd  milk 
usually  falls  between  1.028  and  1.034.  If  the  specific 
gravity  is  either  above  or  below  these  limits  it  is  always 
suspicious.  [The  average  specific  gravity  is  1.032.] 

Many  different  forms  of  apparatus  have  been  pro- 
posed for  measuring  the  transparency  of  milk,  to  deter- 
mine if  it  is  or  is  not  diluted.  However,  these  instru- 
ments are  all  defective  and  the  results  obtained  by  their 
use  are  not  to  be  regarded  as  of  any  value  except  to  indi- 


198  MILK  HYGIENE 

cate  whether  a  sample  of  the  milk  should  be  taken  for 
analysis.  The  transparency  of  milk  is  dependent  partly 
on  the  size  and  number  of  the  fat  globules,  and  partly  on 
the  casein  in  solution.  As  milk  with  fewer,  but  large,  fat 
globules  has  not  the  same  transparency  as  milk  with 
more,  but  smaller,  ones,  even  if  the  fat  per  cent,  be  the 
same,  it  is  evident  that  these  methods  of  examination 
may  give  misleading  results. 

Feser's  lactoscope  is  the  simplest  and  best  instru- 
ment made  for  this  purpose.  As  Fig.  18  shows,  it  con- 
sists of  a  glass  tube  which  narrows  toward  the  bottom 
and  is  closed  with  a  metal  cap  which  supports  a  short 
vertical  glass  column  on  which  are  six  black  lines;  the 
upper  part  of  the  glass  has  divisions  marked  with  a 
double  row  of  figures.  Four  c.c.  of  milk  to  be  examined 
are  poured  into  the  tube,  then  enough  water  is  added 
so  that  it  will  reach  figure  40  (that  is,  36  c.c.  of  water) ; 
the  fluid  is  now  mixed  by  shaking.  If  it  is  not  possible 
to  see  the  lines  on  the  glass  column  inside  the  tube,  a 
little  water  is  added  and  the  tube  is  again  shaken ;  this  is 
continued  until  the  lines  become  visible.  When  they  can 
be  seen  through  the  diluted  milk,  the  fat  per  cent,  can 
be  read  from  the  scale.  For  example,  if  so  much  water 
has  been  added  that  the  fluid  reaches  figure  60  (60  c.c. 
water  and  milk),  then  the  milk  has  3  per  cent.  fat.  As 
already  stated,  this  result  cannot  be  relied  upon ;  in  the 
examination  of  skimmed  milk,  quite  too  high  a  per- 
centage of  fat  is  always  indicated  and,  in  regard  to 
whole  milk,  the  test  may  show  from  0.5  per  cent,  to  1 
per  cent,  too  much  or  too  little. 

On  account  of  the  unreliability  of  this  method  in 
many  places  this  preliminary  test  is  no  longer  used  and 
the  inspectors  take  samples,  without  preliminary  inspec- 
tion, for  examination  in  the  laboratory. 

[In  the  use  of  the  lactoscope,  the  individual  coeffi- 


TRANSPARENCY  TEST 


199 


cient  is  of  great  moment.  Different  inspectors  will  in- 
terpret the  same  result  quite  differently.  When  one  is 
experienced  in  examining  with  the  lactoscope  the  milk 
of  a  given  breed  of  cows,  he  may  become  so  proficient 
that  he  can  make  a  fair  estimate  of  the  fat  content,  but 


FIG.  19. 


FIG.  18. 


Feser's  Lactoscope. 


Queveime's  Lactodensimeter. 


when  another  kind  of  milk  is  examined  the  result  may 
not  be  so  accurate.    If  milk  tests  normally,  both  in  re- 
spect to  specific  gravity  and  lactoscopically,  it  is  not  apt 
to  be  much  skimmed  or  watered. 
The  following  is  from  Leach : 52 

52  A.  E.  Leach,  Food  Inspection  and  Analysis.  New  York,  1905. 


200  MILK  HYGIENE 

"  As  in  the  case  of  the  lactometer,  the  purity  of  a  milk  sample 
cannot  be  positively  established  by  the  lactoscope  alone.  For  instance, 
a  watered  milk  abnormally  high  in  fat  would  often  be  found  to  read 
within  the  limits  of  pure  milk,  when  as  a  matter  of  fact  its  solids 
would  be  below  standard.  By  a  careful  comparison  of  the  readings 
of  both  the  lactoscope  and  the  lactometer,  however,  it  is  rare  that  a 
skimmed  or  watered  sample  could  escape  detection. 

"  Thus,  if  the  specific  gravity  by  the  lactometer  is  well  within 
the  limits  of  pure  milk,  and  the  fat,  as  shown  by  the  lactoscope,  is 
above  3£  per  cent.,  the  sample  may  be  safely  passed  as  pure,  or 
as  conforming  to  the  standard. 

"  A  normal  lactometer  reading  in  connection  with  an  abnormally 
low  lactoscope  reading  shows  both  watering  and  skimming,  and 
with  an  abnormally  high  lactoscope  reading  shows  a  milk  high  in 
fat,  or  a  cream.  With  the  lactoscope  reading  below  three,  and  a 
low  lactometer  reading,  watering  is  indicated.  A  lactometer  reading 
above  thirty-three,  and  a  low  lactoscope  reading,  indicate  skim- 
ming." L.  P.] 

IV.   METHODS  OF  EXAMINATION 

In  order  to  determine  whether  adulteration  has  taken 
place  or  not,  the  examination  should  cover  the  follow- 
ing: The  specific  gravity  of  the  milk  and  of  the  whey, 
the  fat  content  of  the  milk,  the  amount  of  milk  solids, 
the  amount  of  solids  not  fat,  the  specific  gravity  of  the 
solids,  the  quantity  of  fat  [and  the  percentage  of 
ash].  Sometimes,  the  examination  is  extended  to 
include  the  taking  of  a  herd  sample  under  special 
conditions  in  order  to  make  a  comparison  between 
the  sample  officially  collected  and  the  milk  offered  for 
sale.  Finally,  foreign  ingredients  are  tested  for,  as  ni- 
trates, starch,  [preservatives,  artificial  color,  "  visco- 
gen,"  gelatin,  etc.]. 

a.  Taking  samples  for  laboratory  examination  must  be 
conducted  with  great  care.  Upon  standing,  the  cream 
quickly  rises  to  the  top,  so  that  the  upper  part  of  the 
milk  contains  more  fat,  even  though  no  definite  layer  of 
cream  has  yet  been  formed.  Therefore,  before  the  test 


METHODS  OF  EXAMINATION  201 

is  made,  the  milk  should  be  well  mixed.  In  milk  that  has 
been  thoroughly  chilled,  it  is  difficult  to  again  mix  the 
cream  equally,  so  one  must  be  very  exact  in  taking  the 
sample.  It  often  happens,  in  the  milk  shops,  that  the 
milk  is  not  well  mixed  when  sold  and  an  examination 
of  what  is  left  may  show  so  low  a  percentage  of  fat  that 
one  immediately  becomes  suspicious  that  adulteration 
has  taken  place,  although  it  may  not  be  so. 

b.  Preserving  the  sample  for  analysis.    If  the  milk  sam- 
ple is  to  be  kept  or  shipped,  it  is  necessary  to  add  a  pre- 
servative.   For  this,  potassium  dichromate  '(i  grm.  to  1 
liter)  is  used,  which  keeps  the  milk  fluid  for  a  long  time ; 
this  addition  causes  an  increase  in  the  specific  gravity 
and  the  result  of  the  chemical  examination  is  also  af- 
fected.    This  must  be  taken  into  consideration  at  the 
final  test.  It  is  generally  better  to  add  20  drops  of  forma- 
lin to  every  liter,  yet  in  this  case  it  is  possible  that  the 
specific  gravity  of  the  whey  may  be  affected,  on  account 
of  a  partial  splitting  of  the  casein.  It  is  still  better  to  boil 
the  filled  bottle  and  then  close  it  with  a  sterilized  cork. 
In  taking  the  sample,  it  is  also  necessary  to  avoid  adding 
water  even  in  the  slightest  quantity  (rinse  the  bottles 
with  milk),  in  order  that  no  nitrate  shall  be  added. 

c.  The  herd  sample.    In  cases  in  which  adulteration  is 
suspected,  comparison  may  be  made  of  the  milk  under 
suspicion  with  that  of  the  herd  milked  under  super- 
vision.   The  importance  of  the  stable,  or  herd  test  has 
been  much  overestimated.    The  great  variations  in  the 
composition  of  the  milk  of  individual  animals,  leads  one 
to  be  careful  in  putting  confidence  in  a  comparison  of  the 
fat  content  of  milk  on  different  days;  but  comparisons 
may  fairly  be  made  between  the  quantities  of  solids  not 
fat  and  the  specific  gravity  of  the  whey,  which  are  fairly 
regular.     The  stable   or  herd  test  is  very  uncertain, 
therefore,  for  individual  cows,  or  small  herds,  but  it  may 


202  MILK  HYGIENE 

sometimes  be  used  with  advantage  for  large  herds,  al- 
though there  is  seldom  cause,  even  in  this  case,  to 
apply  it. 

In  taking  a  herd  sample,  the  feeding  and  the  care  of 
the  animals  should  not  be  varied  in  any  respect,  the 
milking  should  be  conducted  by  the  usual  persons  at  the 
usual  times  and  in  the  usual  way ;  less  thorough  milking 
gives  lower  fat  content,  while  particularly  thorough 
milking  raises  the  percentage  of  fat.  The  quantity  of 
milk  for  the  day  must  be  mixed  together  and  the  sample 
taken  from  the  whole.  As  transitory  changes  occur  in 
the  composition  of  the  milk,  surer  results  will  be  gained 
from  daily  examinations  for  several  days  than  from  but 
one  examination. 

d.  Determining  the  specific  gravity  of  milk  and  whey. 
Various  instruments  are  used  for  this  purpose :  different 
areometers,  the  pycnometer  or  the  hydrostatic  scale. 
The  areometer  method  is  the  simplest  and,  at  the  same 
time,  it  is  sufficiently  accurate,  so  there  is  no  occasion  to 
describe  more  in  detail  the  other  methods,  which  require 
weighings. 

Quevenne's  lactodensimeter ,  in  some  one  of  its  sev- 
eral modifications,  is  the  areometer  in  common  use. 
This  is  made  like  an  ordinary  areometer  and  divided 
into  degrees  which  correspond  to  a  specific  gravity  from 
1.014  to  1.040,  or  only  from  1.022  to  1.038,  since,  by  the 
latter  division,  a  greater  space  is  gained  between  the 
different  degrees,  without  unduly  lengthening  the  in- 
strument. From  such  a  lactodensimeter  one  can  easily 
read  off  four  decimal  places. 

The  milk  whose  specific  gravity  is  to  be  determined 
is  well  shaken  and  poured  into  a  high  glass  cylinder  of 
suitable  diameter;  the  areometer  is  dropped  in  slowly, 
in  order  to  prevent  its  bobbing  up  and  down.  [The  bulb 
should  be  free  from  adhering  air  bubbles.]  The  figures 


LACTOMETER  TESTS  203 

on  the  stem  are  the  second  and  third  decimals  of  the 
numbers  of  the  specific  gravity,  so  that  34  is  to  be  read 
1.034.  For  this  examination,  the  temperature  of  the 
milk  must  be  15°  C.  (60°  F.) ;  if  it  is  not,  the  specific 
gravity  of  the  milk  at  15°  C.  must  be  calculated  from 
the  specific  gravity  found  and  from  the  temperature, 
for  in  milk  inspection  and  analysis  this  is  the  standard. 
With  the  aid  of  the  tables  on  pages  204  and  205,  one 
of  which  is  valid  for  whole  milk  and  the  other  for 
skimmed  milk,  one  can  easily  compute  specific  gravity 
for  15°  C.  from  that  found  at  another  temperature. 

If  the  temperature  of  the  whole  milk  is  18°  C.,  and 
the  lactodensimeter  reads  29,  one  finds  in  the  table,  at 
the  intersection  of  the  perpendicular  column  18°  C.  and 
the  horizontal  line  1.029,  the  number  29.6;  the  specific 
gravity  is  therefore  equal  to  1.0296  at  15°  C.  (See 
tables,  pages  204  and  205.) 

In  several  of  the  lactodensimeters  (e.g.,  Soxhlet's) 
there  is  a  thermometer  in  the  instrument,  whose  scale 
does  not  show  the  degree  of  heat  but  gives  directly  the 
decimal  to  be  added  to  or  subtracted  from  the  reading 
on  the  stem  of  the  lactodensimeter,  as  the  specific  grav- 
ity. If  the  latter  number  is,  for  example,  29,  and  if  the 
thermometer  registers  3.5  above  zero,  the  specific  grav- 
ity at  15°  C.  is  1.02935. 

[The  so-called  New  York  Board  of  Health  lactometer 
has  an  arbitrary  scale  divided  into  120  equal  parts.  One 
hundred  on  this  scale  corresponds  with  a  specific  gravity 
of  1.029,  which  was  supposed  to  represent  the  lowest 
specific  gravity  of  pure  milk,  and  0  represents  1.000,  the 
specific  gravity  of  water.  If  the  specific  gravity  of  a 
sample  of  milk  fell  to  90  it  was  supposed  to  be  90  per 
cent,  pure,  that  is,  to  contain  10  per  cent,  of  added 
water.  But  the  specific  gravity  of  milk  varies  so  that 
this  cannot  be  relied  on  and  there  is  no  single  advantage 


204 


MILK  HYGIENE 


o 

s 

OsasppppprHCMCMCMCMCOCOCOCOCO 
OS    O    CM    CO    --l"    1C    CO*    t>-    CO'    OS    O    rH    CM    C7    -^°    O    CO 
rHCMCMCMCMCMCMCMCMCMCOCOCOCOCOCOCO 

o 

O 

2 

o 

r^l>-COCCCCCCOOOSOSOSOSOSOOOOO 

o 

O> 

i-H 

OS    O>    rH    CM    CO    "^    1C    CO    t^    CO    OS    <O    CM    CO    "^    1C    CO 
rHCMCMCMCMCMCMCMCMCMCMCOCOCOCOCOCO 

'3 

O 

iciccococococococococo:or^r^r^i>.t^ 

o 

00 
1—  i 

OS    O>    *~H    CM    CO    ~f    iC    CO    t'—    CO    OS    O1    rH    CM    CO    ^    1C 
rHCMCMCMCMCMCMCMCMCMCMCOCOCOCOCOCO 

3 

^eo^^^^^^^^^^^^^^^ 

o 

t- 

I—  1 

OS    O>    ^^    C^-i    CO    "^    iC    CO    ^  ^*    ^0    O^    CJ    I-H    7^    CO    ~^    i  C 
i-HCMCMC^lCMCMCMC^CMCMCMCOCOCOCOCOCO 

CD 

S 

o 

r-i-HCMCMCMCMCMCMCMCM<MCMCMCMCMCMCM 

o 

CD 

os  o  rH  CM'  co"  H^  ic  co  t^-  co"  os  o  r-I  c^-i  c^  -^H  »o 

rHCMCMCMCMCMCMCMCMCMCMCOCOCOCOCOCO 

S 

0 

O    O    O    O   O   O    O    0    O    OOOOOOOO 

0 

10 

rH) 

OS    O>    rH    CM    CO    "^    1C    CO    t^-    CO    OS    <O    *H    CM    CO    "^    1C 
rHCMCMCMCMCMCMCMCMCMCMOOCOCOCOCOCO 

g 

0 
i—  1 

COCOCOCOCOCOCOCOCOCOCOCOCOCOCOOOt^ 

co  os*  o  rH  CM'  co  T*H  10  co  t^"  co  os  o  -H  CM'  co  -t* 

rHrHCMCMCMCMCMCMCMCMCMCMCOCOCOCOCO 

10 

1 

5 

O 

r^cDCOcOcOcOCOcOCOcOcOCOcOcoCOiCTjH 

o 

i 

CO 
i—  I 

COOSOrHCMCOH/tlOCOr^aOOSOrHCMCOT^ 
rHrHCMCMCMCMCMCMCMCMCMCMCOCOCOCOCO 

g 

3 

0 

S 

CM 
i—  1 

COOSOrHCMCOH^lOCOt^COOSOrHCMCO-h 
rHrHCMCMCMCMCMCMCMCMCMCMCOCOCOCOCO 

CO 
10 

1 

0 

H 

i-H 
i—  1 

GO     OS     O    rH     CM     CO     H/l     1C     CO     t^    CO    OS     O     rH     CM     CO     -^ 
i—  IrHCMCMCMCMCMCMCMCMCMCMCOCOCOCOCO 

S 

0 

-tHCOCOCOCOCOCMCMCMT—  IrHOOOOOSCO 

0 

0 
i—  I 

COOSOrHCMCO^lCCOI^-COOSOrHCMCvJCO 
rHrHCMCMCMCMCMCMCMCMCMCMCOCOCOCOCO 

1 

COCMCMCMCMCMrHrHrHOOSCOCOCOQOl^CO 

0 

OS 

COOSOrHCMCO-flCCOr^-    t^-COOSOi—  l<MCO 
rHrHCMCMCMCMCMCMCMCMCMCMCMCOCOCOCO 

^ 

0 

CO 

COOSOrHCMCOTfiCCOCOt^-CCOSO'—  iC-^CO 
rHrHCMCMCMCMCMCMCMCMCMiMCMCOCCCOCO 

1 

rHOOOOOOSOSOSCOI^COCOiC-*"COCM 

CO 

g- 

COOSOrHCMCOCO-^lCCOJ^COOSOrHtMCO 
i—  irHCMCMCMCMCMCMCMCMCMCMCMCOOOCOCO 

rHOOSOSOSOSCOCOQOt^OlClC-^OOCMrH 

00 

CD 

COOSOSOi—  iCMCOH^iCCOt^COOSOrHCMCO 
r_,Ti,r_iCMCMCMCMCMCMCMCMCM(MCOCOCOCO 

fi 

0 

CT5   CO   rH]   CM   CO   ^^   *O   CD   t^*   00    O5   CO   rH   CM   CO   ^i^    ^O 
rH<M(MCMCMC<l<M<MC<ICM(NCOCOCOCOCOCO 

I 

SPECIFIC  GRAVITY  DETERMINATION    205 


c 


oo 


00 


-f 
<M 


CO    CO    CO    CO    CO    CO    CO    <M_    <M    CO 

I-H  CO  CO  -t  iO  CO  t^  00  CJ  O 


oooooooooooooooooo 


OO  OO  00  QO  OO  GO  OO  00  GO  OO  OO  OO  00  GO  00  00 


t^^ioiqioioiqioioioioiq 


cqiOTjH^Ttj'^'*'*.  T*?^'*.  T^wwoooqccco 


•^    CO    CO    C<j    CO    CO    CO    CO    (M_    CO    CO    CO    I-H    r*    I-H    I-H    p    OS 

c^ico^^ccdt^-oooiorHcoco-^iocDt^odoc 

C^-l  CO  CO  CO  CO  CO  CO  CO  CO  00  CO  CO  CO  CO  CO  CO  CO  CO 


O  O  O  O  Ol  00 


CO  CO  r-j  — J  T-H  I-H  rH  O  O  O  Q  O  Ol  Ol  Oi  OS  GO  t-- 


CO  CO 


OOOSOCOOOOOOl^CO 


(M<M<M<M<M<MCOCOCOCOCOeOCOOOCOCO^ 


S 


10 


S 


10 


3 


9 


206 


MILK  HYGIENE 


in  this  arbitrary  scale,  which  is  very  confusing.  Un- 
fortunately, however,  it  has  come  into  rather  general 
use  among  milk  inspectors,  especially  in  the  Eastern 
States. 

To  convert  readings  of  this  lactometer  into  corre- 
sponding readings  of  the  Quevenne  scale,  they  must  be 
multiplied  by  0.29,  or,  the  following  table  may  be  used : 

QUEVENNE  LACTOMETER  DEGREES  CORRESPONDING 

TO  NEW  YORK  BOARD  OF  HEALTH 

LACTOMETER  DEGREES. 


Board  of 
Health 
Degrees. 

Quevenne 
Scale. 

Board  of 
Health 
Degrees. 

Quevenne 
Scale. 

Board  of 
Health 
Degrees. 

Quevenne 
Scale. 

61 

17-7 

81 

23-5 

101 

29-3 

62 

18-0 

82 

23-8 

102 

29-6 

63 

18-3 

83 

24-1 

103 

29-9 

64 

]8-6 

84 

24-4 

104 

30-2 

65 

18-8 

85 

24-6 

105 

30-5 

66 

19-1 

86 

24-9 

106 

30-7 

67 

19-4 

87 

25-2 

107 

31-0 

68 

19-7 

88 

25-5 

108 

31-3 

69 

20-0 

89 

25-8 

109 

31-6 

70 

20-3 

90 

26-1 

110 

31-9 

71 

20-6 

91 

26-4 

111 

32-2 

72 

20-9 

92 

26-7 

112 

32-5 

73 

21-2 

93 

27-0 

113 

32-8 

74 

21-5 

94 

27-3 

114 

33-1 

75 

21-7 

95 

27-6 

115 

33-4 

76 

22-0 

96 

27-8 

116 

33-6 

77 

22-3 

97 

28-1 

,     117 

33-9 

78 

22-6 

98 

28-4 

118 

34-2 

79 

22-9 

99 

28-7 

119 

34-5 

80 

23-2 

100 

29-0 

120 

34-8 

L.P.] 


Specific  gravity  of  the  ivhey.  In  many  cases  it  is  of 
value  to  determine  the  specific  gravity  of  the  whey  be- 
cause this  is  much  more  constant  than  that  of  milk, 
for  the  reason  that  the  lactose  and  salt  vary  less  than 
the  fat. 


SPECIFIC  GRAVITY  OF  WHEY  207 

Leseoeur  warms  the  milk  to  45°  C.  (113°  F.)  and  adds  rennet; 
after  about  one-half  hour  the  whey  is  pressed  out  and  filtered,  then 
it  is  cooled  to  exactly  15°  C.;  the  specific  gravity  may  then  vary 
between  1.029  and  1.031,  but  if  water  has  been  added  it  decreases 
significantly,  as  shown  below: 

Whey  of  pure  milk  =1.0300 

Whey  of  milk  + 10  per  cent,  water  =  1.0275 

Whey  of  milk  -f-  20  per  cent,  water  =  1.0251 

Whey  of  milk  -J-  30  per  cent,  water  =  1.0230 

Reich  recommends  that  20  c.c.  glacial  acetic  acid  be  added  to 
500  c.c.  milk,  that  the  mixture  be  well  shaken  and  heated  for 
5  to  6  minutes  to  60°  to  65°  C.  (140°  to  150°  F.)  in  a  closed  flask,  then 
cooled  and  filtered ;  the  filtrate  is  to  be  heated  in  a  flask  until  the  albu- 
min coagulates,  then  filtered  again  and  the  specific  gravity  determined 
after  cooling  to  15°  C.  According  to  his  results,  this  varies  between 
1.027  and  1.029;  a  specific  gravity  of  1.026  is  always  a  sign  of  the 
addition  of  water. 

If  one  wishes  to  apply  the  determination  of  specific 
gravity  of  whey  to  milk  inspection,  it  is  necessary  to 
develop  a  definite  method,  which  must  be  followed  out 
exactly,  for,  otherwise,  the  result  is  uncertain;  and  be- 
fore basing  a  prosecution  on  the  results  of  this  method, 
one  must  have  made  careful  comparisons,  with  the  same 
method,  of  normal  and  watered  milks. 

From  investigations  that  were  undertaken  in  Copen- 
hagen under  Jensen's  direction,  it  appears  that  these 
two  methods  do  not  give  uniform  results.  From  35 
milk  samples  the  following  results  were  obtained: 

Rennet  method  Acid  method 

Specific  gravity  Specific  gravity 

7  samples  1.0270  to  1.0274  2  samples  1.0257  to  1.0259 

7        "        1.0275  to  1.0279  10         "        1.0260  to  1.0264 

15        "        1.0280  to  1.0284  15         "        1.0265  to  1.0269 

6        "        1.0285  to  1.0290  8        "        1.0270  to  1.0276 


208  MILK  HYGIENE 

The  addition  of  water  causes  a  lower  specific  gravity 
of  the  whey.  In  the  examination  of  adulterated 
skimmed  milk,  he  found  the  figures  to  be  1.0256,  1.0246, 
1.0254  and  1.0257  (rennet  method)  and  1.0242,  1.0234, 
1.0238  and  1.0241  (acid  method). 

e.  The  determination  of  the  fat  content  of  milk.  There 
are  many  methods  for  determining  the  fat  content  of 
milk;  some  of  these  are  too  inexact  to  be  considered 
(e.g.,  the  above  mentioned  transparency  test  by  means 
of  the  lactoscope,  and  the  like),  others  give  very  good 
results  but  require  rather  expensive  apparatus,  still 
others  require  exact  weighings  and  work  that  can  be 
done  only  in  chemical  laboratories.  Some  simple  tests 
are,  however,  so  accurate  and  so  practical  that  they  are 
available  for  the  work  of  milk  inspection. 

Among  the  methods  used,  besides  the  transparency 
test  already  mentioned,  the  creamometer  should  be 
named,  that  is,  the  measurement  of  the  layer  of  cream 
which  rises  when  the  milk  is  allowed  to  stand.  Since, 
however,  the  thickness  of  the  layer  of  cream  furnishes 
no  reliable  gauge  as  to  the  fat  content,  this  method  can- 
not be  used  if  there  is  to  be  a  prosecution.  The  separa- 
tion of  the  cream  by  a  centrifuge  of  high  velocity 
(Fjord's  test),  and  subsequently  measuring  the  layer  of 
cream,  gives  better  results  and  is  often  used  in  cream- 
eries for  comparing  milks.  For  general  use,  however, 
it  is  impractical,  and  not  sufficiently  accurate. 

The  available  methods  are,  principally,  Soxhlet's 
method,  which  was  formerly  used  to  a  greater  extent 
than  it  is  now;  Gerber's  method,  [the  Leffmann-Beam 
and  the  Babcock  methods]  and  methods  of  chemical 
analysis. 

Soxhlet's  method  is  founded  upon  the  following  prin- 
ciple :  the  solution  of  the  fat  in  ether  and  the  determina- 
tion of  the  specific  gravity  of  this  solution. 


GERBER'S  FAT  DETERMINATION         209 

The  following-  appliances  are  necessary  for  this  examination  (see 
Fig.  20):  (1)  three  pipettes  of  200,  60  and  10  c.c.;  (2)  several 
half  liter  bottles;  (3)  two  delicate  areometers  with  thermometer, 
onte  for  whole  milk  and  the  other  for  skimmed  milk;  (4)  one  large 
glass  tube  (A)  adjusted  for  flowing  water;  (5)  a  smaller  glass 
tube  (B)  enclosed  in  A;  (6)  a  rubber  bulb  with  a  tube;  (7)  a  larger 
container  filled  with  water  heated  to  17°  to  18°  C.  Besides  these,  the 
following  chemicals  are  necessary:  (8)  potassium  hydroxide  solution 
of  specific  gravity  1.27  (400  gr.  potassium  hydroxide  is  dissolved  in 
water  and  after  the  solution  has  cooled  it  is  made  up  to  1  liter)  ;  (9) 
ether,  shaken  with  one-fifth  its  volume  of  water  and  decanted  off; 
(10)  ordinary  ether. 

The  milk  to  be  examined  is  warmed  in  a  water  bath  to  18°  C.  and 
is  well  shaken.  By  means  of  a  pipette,  200  c.c.  of  this  are  drawn 
off  and  mixed  in  a  bottle  with  10  c.c.  of  the  potassium  hydroxide 
solution.  Then,  60  c.c.  of  ether  are  added.  The  bottle  is  immediately 
closed  by  a  perfectly  tight  stopper,  is  violently  shaken  and  allowed  to 
stand  one-fourth  hour  in  water  at  18°  C.,  during  which  time  it  must  be 
shaken  frequently.  Gradually,  the  ether  dissolves  the  fat  and  a 
transparent  layer  is  formed  on  the  surface.  Now  the  stopper  of 
the  bottle  is  replaced  by  another  (D)  and,  by  means  of  a  bulb,  the 
transparent  fat-containing  ether  is  driven  up  into  the  tube  B  which  is 
surrounded  in  tube  A  by  water  warmed  to  18°  C.  The  areometer 
(C)  is  in  the  inner  tube,  and  after  the  fluid  rises  so  high  that  it 
can  float,  the  flow  is  checked  by  means  of  a  valve  q,  then  the 
specific  gravity  is  read.  The  quantity  of  fat  dissolved  is  shown,  and 
from  this  -the  fat  content  of  the  milk  can  be  calculated.  Soxhlet's 
apparatus  is  accompanied  by  tables  from  which  the  fat  content  of  the 
milk  can  easily  be  read,  if  one  has  determined  the  specific  gravity 
of  the  fat-ether,  and  has  read  its  temperature. 

Gerber's  acidobutyro  meter  affords  a  very  convenient 
and  accurate  way  of  determining  fat,  that  is  widely 
used.  The  method  consists  in  measuring  the  quantity 
of  fat  in  an  accurately  measured  quantity  of  milk,  after 
the  fat  has  been  separated  and  dissolved  in  amyl-alco- 
hol.  Gerber's  instrument  (see  figs.  21  and  22),  consists 
of  a  centrifuge,  bottles  (G)  of  special  shape,  and  3 
pipettes, i.e. :  1  acid  pipette  to  hold  10  c.c.(H)  and  2  small 
pipettes  (I,  K)  of  1  and  11  c.c.  capacity.  These  chem- 

14 


210 


MILK  HYGIENE 


icals  are  required:  crude  sulphuric  acid  of  a  specific 
gravity  at  15°  C.  (60°  F.)  of  1.825,  and  amyl-alcohol. 
The  examination  is  made  in  the  following  way:  10  c.c. 


FIG.  20. 


Soxhlet's  apparatus  for  fat-determination. 


of  sulphuric  acid  are  measured  out  by  the  acid  pipette, 
this  is  permitted  to  flow  slowly  into  the  bottle  G;  1  c.c. 
of  amyl-alcohol  is  measured  and  poured  carefully  into 


GEKBER'S  FAT  DETERMINATION        211 

the  glass  so  that  it  forms  a  layer  upon  the  surface  of 
the  sulphuric  acid.  Now,  exactly  11  c.c.  of  well  mixed 
milk  that  has  been  heated  to  15°  C.  (60°  F.)  are  measured 
and  poured  into  the  bottle,  which  is  closed  by  a  rubber 
stopper  and  then  it  is  well  shaken.  The  milk  dissolves 
with  the  generation  of  considerable  heat.  The  stopper 
is  driven  in  so  far  that  in  the  inverted  bottle,  the  fluid 

FIG.  21. 


Gerber's  apparatus  for  fat-determination. 

reaches  the  mark  0  on  the  scale ;  the  bottle  is  put  into  the 
centrifuge  and  this  is  set  in  motion,  after  it  has  been 
well  balanced.  If  the  sample  is  not  to  be  centrifuged  at 
once,  the  bottle  should  be  placed  in  a  water  bath  at  60° 
to  65°  C.  (140°  to  150°  F.).  The  process  of  centrifuging 
lasts  10  minutes  with  such  a  machine  as  shown  in  figure 
21 ;  and  in  order  to  keep  up  speed  it  is  necessary  to  ac- 


212 


MILK  HYGIENE 


celerate  the  motion  three  times,  by  drawing  the  strap. 
[With  some  patterns  of  centrifuge,  those  that  have  a 
velocity  of  800  to  1000  per  minute,  the  whirling  is  com- 
pleted in  3  to  4  minutes.]  After  centrifuging,  the  bottle 
is  taken  out  and  placed  in  a  water  bath  at  60°  C.  (140° 
F.).  The  fat  forms  a  clear  layer  in  the  top  of  the  tube. 
Through  shifting  the  stopper,  the  lower  border  of  the 


Fro.  22. 


Test  bottles  and  pipettes  used  in  connection  with  Gerber  s  method  for  fat-determination. 

fat  layer  can  be  brought  into  the  same  plane  with  one  of 
the  division  lines  and  the  thickness  of  the  layer  of  fat 
can  be  read  off.  One  should  read  from  the  lower  part 
of  the  curved  upper  line.  The  upper,  narrow  part  of 
the  tube  is  divided  in  90  parts,  each  line  corresponds  to 
0.1  per  cent,  fat;  for  example,  if  the  fat  layer  reaches 
line  35,  then  the  fat  content  of  the  milk  is  3.5  per  cent. 


LEFFM ANN'S  FAT  DETERMINATION     213 

[The  Leffmann-Beam  method  (sometimes,  improp- 
erly, called  the  Beimling  test)  was  worked  out  in  ad- 
vance of  the  Gerber  test,  which  resembles  it.  The  fol- 
lowing description  is  from  Leffmann : 53  "  The  dis- 
tinctive feature  is  the  use  of  fusel  oil,  the  effect  of  which 
is  to  produce  a  greater  difference  in  surface  tension 
between  the  fat  and  the  liquid  in  which  it  is  suspended, 
and  thus  promote  its  readier  separation.  This  effect 
has  been  found  to  be  heightened  by  the  presence  of  a 
small  amount  of  hydrochloric  acid. 

"  The  test  bottles  have  a  capacity  of  about  30  c.c. 
and  are  provided  with  a  graduated  neck,  each  division 
of  which  represents  0.1  per  cent.,  by  weight,  of  butter 
fat. 

"  Fifteen  c.c.  of  the  milk  are  measured  into  the  bot- 
tle, 3  c.c.  of  a  mixture  of  equal  parts  of  amyl-alcohol 
and  strong  hydrochloric  acid  added,  mixed,  the  bottle 
filled  nearly  to  the  neck  with  concentrated  sulphuric  acid, 
and  the  liquids  mixed  by  holding  the  bottle  by  the  neck 
and  giving  it  a  gyratory  motion.  The  neck  is  now  filled 
to  about  the  zero  point  with  a  mixture  of  sulphuric  acid 
and  water  prepared  at  the  time.  It  is  then  placed  in 
the  centrifugal  machine,  which  is  so  arranged  that  when 
at  rest  the  bottles  are  in  a  vertical  position.  If  only  one 
test  is  to  be  made,  the  equilibrium  of  the  machine  is 
maintained  by  means  of  a  test  bottle,  or  bottles,  filled 
with  a  mixture  of  equal  parts  of  sulphuric  acid  and 
water.  After  rotation  for  from  one  to  two  minutes,  the 
fat  will  collect  in  the  neck  of  the  bottle  and  the  percent- 
age may  be  read  off.  It  is  convenient  to  use  a  pair  of 
dividers  in  making  the  reading.  The  legs  of  these  are 
placed  at  the  upper  and  lower  limits  respectively  of  the 
fat,  allowance  being  made  for  the  meniscus;  one  leg  is 

53  Henry  Leffmann,  Analysis  of  Milk  and  Milk  Products.  Phila- 
delphia, 1905. 


214  MILK  HYGIENE 

then  placed  at  the  zero  point  and  the  reading  made  with 
the  other.  Experience  by  analysts  in  various  parts  of 
the  world  has  shown  that  with  properly  graduated 
bottles  the  results  are  reliable.  As  a  rule,  they  do  not 
differ  more  than  0.1  per  cent,  from  those  obtained  by 
the  Adam's  process,  and  are  generally  even  closer. 

"  The  mixture  of  fusel  oil  and  hydrochloric  acid 
seems  to  become  less  satisfactory  when  long  kept.  It 
should  be  clear  and  not  very  dark  in  color.  It  is  best 
kept  in  a  bottle  provided  with  a  pipette,  which  can  be 
filled  to  the  mark  by  dipping.  Rigid  accuracy  in  the 
measurement  is  not  needed." 

The  Babcock  method  or  "  test  "  is,  in  America,  by 
far  the  best  known  and  most  used  centrifugal  test  for  fat 
in  milk.  The  Leirmann-Beam  and  the  Gerber  tests  are, 
however,  being  used  more  and  more,  on  account  of  the 
shorter  time  required. 

In  careful  hands,  the  Babcock  test  is  very  accurate. 
Small  or  large  outfits,  the  centrifuges  to  be  driven  by 
hand  or  power,  may  be  purchased  from  any  dairy  sup- 
ply establishment.  The  test  is  made  by  placing  in  the 
special  test  bottle  18  grams  (17.6  c.c.)  of  milk.  To  this 
is  added,  from  a  pipette,  burette  or  measuring  bottle, 
17.5  c.c.  commercial  sulphuric  acid  of  a  specific  gravity 
of  1.82  to  1.83.  The  contents  of  the  bottle  are  carefully 
and  thoroughly  mixed  by  a  rotary  motion.  The  mixture 
becomes  brown  and  heat  is  generated.  The  test  bottle  is 
now  placed  in  a  properly  balanced  centrifuge  and 
whirled  for  five  minutes  at  a  speed  of  from  800  to  1200 
revolutions  per  minute.  Hot  water  is  then  added  to  fill 
the  bottle  to  the  lower  part  of  the  neck,  after  which  it 
is  again  whirled  for  two  minutes.  Now,  enough  hot 
water  is  added  to  float  the  column  of  fat  into  the  grad- 
uated portion  of  the  neck  of  the  bottle,  and  the  whirling 
is  repeated  for  a  minute. 


BABCOCK'S  FAT  DETERMINATION       215 

The  amount  of  fat  is  read  while  the  neck  of  the  bottle 
is  still  hot.  The  reading  is  from  the  upper  limits  of  the 
mensicus  instead  of  the  lower,  as  with  the  Gerber  and 
the  Leffmann-Beam  tests.  A  pair  of  calipers  is  of  as- 
sistance in  measuring  the  column  of  fat.  L.  P.] 

The  chemical  methods  consist  in  accurately  weighing 
the  fat  separated  from  a  definite  quantity  of  milk.  The 

FIG.  23. 


One  form  of  Babcock's  apparatus  for  fat-determination.* 

most  exact  result  is  gained  by  the  evaporation  of  a  defi- 
nite amount  of  milk  (see  below)  and  by  the  extraction 
of  the  fat  from  the  evaporated  mass  by  ether  or  benzine, 
which  is  then  evaporated.  Quite  accurate  results  are 
also  gained  without  evaporating  the  milk,  by  separating 

*  From  "  Principles  and  Practice  of  Butter-Making,"  by  McKay 
and  Larsen,  by  permission  of  Messrs.  John  Wiley  &  Sons,  the 
publishers. 


216  MILK  HYGIENE 

the  fats  from  the  other  ingredients  and  ascertaining 
their  weight. 

Gottleib's  method  gives  results  sufficiently  accurate  for  our  use. 
For  this  method  one  requires,  as  apparatus,  only  a  cylinder  of  40  c.c. 
capacity,  divided  to  measure  quantities  of  0.5  c.c.,  some  glass  flasks 
and  a  long,  thin  glass  syphon.  10  grm.  of  milk  are  accurately  weighed 
into  one  of  the  small  flasks  and  poured  into  the  glass  cylinder;  the 
amount  of  milk  left  adhering  to  the  walls  of  the  flask  is  determined 
by  a  second  weighing,  so  that  one  may  know  exactly  how  much 
has  been  poured  into  the  cylinder.  1  c.c.  of  10  per  cent,  ammonia 
water  (specific  gravity  0.96)  is  mixed  with  the  milk  and  shaken, 
then  10  c.c.  alcohol  (95  per  cent.)  are  added  and  it  is  shaken  again, 
after  which  25  c.c.  ether  are  added.  The  cylinder  is  well  closed  with 
a  cork  that  has  been  moistened  in  water,  and  shaken  hard.  25  c.c. 
petroleum  benzine  are  added  and,  after  repeated  shaking,  the  bottle 
should  be  allowed  to  stand  undisturbed  at  least  6  hours.  By  that 
time,  the  fluid  is  separated  into  two  sharply  marked  layers;  the 
upper  one  is  the  ether-benzine-fat  mixture,  the  under  one  contains 
the  water,  the  lactose  and  proteids;  a  whitish  sediment  consists  of 
phosphates.  The  volume  of  the  upper  layer  of  the  fluid  is  read  off 
and  a  determined  quantity  of  it  is  syphoned  off  into  a  small  weighed 
flask.  The  ether  and  benzine  are  now  evaporated  by  mild  heat. 
Thereupon,  the  flask  is  allowed  to  stand  a  couple  of  hours  in  a  drying 
chamber  at  100°  C.,  is  cooled  in  an  exsiccator  and,  finally,  weighed. 
From  the  total  volume  of  the  mixture  of  ether,  benzine  and  fat, 
and  from  the  quantity  of  fat  in  the  portion  evaporated,  the  weight  of 
the  total  fat  content  of  the  milk  sample  can  be  calculated,  and  thus 
the  percentage  is  determined. 

/.  Determination  of  the  total  solids  in  milk.  The  total 
solids  in  milk  are  determined  chemically  in  the  following 
way :  Exactly  10  c.c.  of  milk  are  measured  into  a  plat- 
inum or  porcelain  vessel,  the  weight  of  which  is  already 
known;  the  vessel  is  heated  in  a  water  bath  to  100°  C. 
until  all  the  water  is  evaporated.  After  cooling  in  an 
exsiccator,  the  vessel  and  its  contents  are  weighed.  The 
difference  between  the  weight  found  and  the  original 
weight  of  the  dish  gives  the  total  amount  of  solids  in 
the  milk.  If  the  amount  of  fat,  found  in  another  way,  is 


DETERMINATION  OF  SOLIDS  217 

subtracted,  one  gets  the  quantity  of  solids  not  fat.  By 
incinerating  tlie  contents  of  the  vessel,  in  a  muffle  oven, 
and  again  weighing,  the  amount  of  salts,  or  ash,  is  deter- 
mined. If  it  is  desired  to  extract  the  fat  from  the  other 
solids,  to  determine  the  fat  percentage,  it  is  necessary 
before  drying  the  milk  to  mix  with  it  a  weighed  quantity 
of  roasted  pumice  stone  ;  then,  after  evaporation,  the  fat 
is  removed  by  means  of  ether  (or  benzine)  in  an  ordi- 
nary fat  extraction  apparatus,  and  is  determined  by 
weighing,  after  evaporating  the  ether.  This  work  is 
quite  particular  and  requires  a  well  appointed  labora- 
tory. Moreover,  in  practical  milk  control,  gravimetric 
analyses  are  not  indispensable,  for  one  can  easily  cal- 
culate the  quantity  of  solids  from  the  specific  gravity 
and  the  fat,  according  to  the  formula  derived  by  Fleisch- 
mann.  If  total  solids  are  represented  by  t,  the  fat  per 
cent,  by  f  and  the  specific  gravity  by  s,  one  has  : 


=  :.2  X  f  +  2.665  X 


That  is,  if  we  say  f  =  3.55  and  s  z=  1.0327,  we  get 


100  X  1.0327  -  100  \   Anan  ,  2.665  X  3.27 


t  -  1.2  X  3.55  +  (2.665  X  10°  *  ^  ~  10°  )  =  4- 


4.260  + 


Another  formula  proposed  by  Bertschinger  gives  quite 
accurate  results  : 


Moreover,  tables  have  been  worked  out  from  which 
the  total  solids  can  be  read  off,  if  both  the  other  factors 
are  known.  Ackermann  has  constructed  an  '  '  automatic 
reckoner  "  from  which  one  can  read  off  one  of  the  fac- 
tors when  both  of  the  others  are  known,  by  simply  turn- 
ing circular  discs.  [Richmond  has  devised  a  sliding  rule 
for  the  same  purpose.] 

The  computation  of  the  solids  not  fat  is  very  easy. 


218  MILK  HYGIENE 

One  has  only  to  subtract  the  fat  percentage  found  from 
the  computed  percentage  of  total  solids.  The  percent- 
age of  fat  (p)  in  the  total  solids  is  easily  computed 
according  to  the  formula: 

P  =  4-  x  100 

ll 

To  use  the  above  illustration  : 

O   KK 


Likewise,  it  is  quite  easy  to  determine  the  specific 
gravity  (m)  of  the  dry  milk  solids  by  a  simple  computa- 
tion, according  to  this  formula  : 


st 


st  —  (100s  —  100) 

Using  the  same  illustration  again: 

_ 1.0327  X  12.697  13.112    _ 

1. 0327  X  12.697—  (103.27  — 100)    13.112  — 3.27  ~ 

The  specific  gravity  of  the  dry  solids  of  whole  milk 
varies,  according  to  the  fat  content,  between  about  1.31 
and  1.36. 

V.     ADULTERATION  AND  ITS  DETECTION. 

The  most  frequent  adulterations  of  whole  milk  con- 
sist in  partial  skimming,  dilution  with  skimmed  milk, 
dilution  with  water  or  a  combination  of  these.  Skimmed 
milk  is  adulterated  by  the  addition  of  water,  and  cream 
by  starch,  flour,  etc. 

a.  Partial  skimming  of  whole  milk  or  dilution  with 
skimmed  milk  produce  the  same  result ;  in  both  cases 
the  fat  content  is  lessened,  while  the  percentage  of  solids 
not  fat  is  increased  very  slightly,  and  the  specific  gravity 
is  increased.  If  the  skimming  is  not  so  great  as  to  cause 
the  fat  percentage  to  fall  below  the  minimum  limit  for 


DETECTION  OF  ADULTERATION         219 

mixed  milk  and  the  specific  gravity  to  rise  above  its 
maximum  (1.034),  this  adulteration  is  difficult  to  dis- 
cover, as  the  considerable  variations  in  normal  milk 
would  lead  one  to  expect.  It  is  in  these  cases  that  com- 
parison was  formerly  made  with  the  stable  or  herd  sam- 
ples, but,  as  stated  before,  these  are  worth  but  little  in 
relation  to  small  herds,  and  even  in  the  case  of  large 
ones  they  are  not  entirely  trustworthy.  When  it  is  pos- 
sible to  compare  the  figures  of  inspected  milk  with  the 
results  of  the  herd  test,  an  opinion  can  be  formed  as  to 
how  great  a  percentage  of  the  fat  content  is  lacking, 
from  this  formula  : 

x  =  100  X 


in  which  F  shows  the  fat  percentage  in  the  herd  sample 
and  f  the  fat  percentage  of  the  sample  under  suspicion. 

Where  there  is  reason  for  suspicion,  the  best  method 
for  proving  the  existence  of  such  adulteration  is, 
in  many  cases,  furnished  by  the  judicial  hearing  of  the 
persons  charged,  and  the  witnesses.  In  many  places,  as 
has  already  been  stated,  to  prevent  such  adulterations  a 
minimum  standard  has  been  established  for  the  fat  con- 
tent of  whole  milk. 

[In  America,  where  there  are  legal  standards  calling 
for  3  to  3.5  per  cent,  of  fat  in  whole  milk,  prosecutions 
for  partial  skimming  or  dilution  with  skimmed  milk  are 
not  often  brought  if  the  sample  comes  up  to  this  estab- 
lished standard,  although  such  adulteration  may  be 
suspected  from  a  marked  disproportion  between  the 
fat  and  the  solids  not  fat.  But  this  proportion  is,  at 
best,  so  variable  that  it  furnishes  no  definite  guide. 
L.P.] 

b.  The  dilution  of  whole  milk  with  water  causes  an 
increase  of  volume  and,  therefore,  a  decrease  in  the  per- 
centage of  fat,  of  solids  and  of  the  specific  gravity  of  the 


220  MILK  HYGIENE 

milk,  as  well  as  of  the  whey.  Feser  gives  the  following 
example  : 

Start  with  9  liters  of  milk  of  the  composition  :  3.95 
per  cent.,  fat  ;  8.9  per  cent.,  solids  not  fat  ;  1.031,  specific 
gravity. 

To  this  add  1  liter  of  water  of  this  composition  :  0  per 
cent.,  fat;  0  per  cent.,  solids  not  fat;  1.000,  specific 
gravity. 

This  gives  10  liters  of  adulterated  milk  of  the  com- 
position: 3.55  per  cent.,  fat;  about  8.0  per  cent.,  solids 
not  fat  ;  1.028,  specific  gravity. 

Further  evidence  of  this  adulteration  is  found  in  the 
lower  specific  gravity  of  the  whey  and  in  the  fact  that 
the  specific  gravity  of  the  dry  solids  (m)  and  the  fat 
content  (p)  of  the  solids  are,  practically,  normal;  in  the 
above  example,  then  :  54 

__  ST  1.031  X  12.85  13.24  _ 

~  ST  —  (100S  —  100)       1.031  X  12.85  —  (100  X  1.031  —  100)       10.14 

_  _  st  _  1.028  X  11.55  _  =  11.873  . 

~~  St  —  (100s  —  100)  1.028  X  11.55  —  (100  X  1.028  —  100)          9.073 

•p  O    QK 

P  =  .£-  X  100  ^frp-  X  100  =  30.738 

T  ll&.oO 

p  ==  -*-  X  100  ==  ~j-  X  100  =  30.736 


If  milk  samples  are  available  which  may  be  justly  com- 
pared with  the  milk  under  suspicion  (herd  samples 
taken  under  fixed  conditions  ;  milk  from  the  same  large 
herd;  other  milk  sent  by  the  same  shipper  or  from  the 
same  can  in  the  dealer's  possession),  then  the  percent- 
age of  water  added  can  be  computed  according  to  Vo- 
gel  's  formula  : 

x  =  --X  100-=-  100 


54  [M  and  P  represent  the  specific  gravity  of  the  total  solids  and 
the  percentage  of  fat  in  the  total  solids  of  whole  milk,  and  m  and 
p  the  same  factors  in  adulterated  milk.] 


DETECTION    OF    ADULTERATION         221 

In   the   example   just   given   we  have   F  =  3.95   and   f 
=  3.55,  then 

q  OK 

x  =  2™  X  100  -r-  100  =  11.11  % 

o.OO 


that  is,  exactly  1  part  to  9  parts.  On  account  of  the 
great  variations  in  the  percentage  of  fat,  one  must  be 
very  careful  with  this  computation. 

In  detecting  this  adulteration,  the  herd  sample  is  of 
some  value,  since  the  solids  not  fat  are  subject  only  to 
slight  variations.  In  drawing  conclusions,  therefore, 
these  other  factors  must  have  full  consideration  (esti- 
mated solids  not  fat,  specific  gravity  of  the  whey),  and 
are  of  more  value  as  a  guide  than  the  percentage  of  fat. 

[The  percentage  of  solids  not  fat  should  not  be  less 
than  8.5  or  9.  The  percentage  of  ash  is  of  considerable 
value  in  detecting  adulteration  by  adding  water.  This 
factor  is  rather  constant,  and  in  pure  milk  is  usually 
between  0.70  and  0.75  per  cent.  L.P.] 

It  has  been  suggested  that  use  be  made  of  the  deter- 
mining of  the  freezing  point  of  milk  and  of  its  conducti- 
bility  for  electricity,  since  these  qualities  are  consid- 
erably changed  by  the  addition  of  water.  But  these 
methods  are  not  yet  sufficiently  developed  to  be  avail- 
able. On  the  other  hand,  there  may  be  some  advantage 
in  determining  the  acidity  of  the  milk,  since  this  is  less- 
ened by  dilution  (see  page  227),  yet  the  lessened  acidity 
may  come  from  other  causes. 

The  addition  of  lactose  or  cane  sugar  to  milk  diluted 
with  water,  renders  judgment  more  difficult,  since,  by 
this  means,  the  specific  gravity  of  the  milk  as  well  as 
that  of  the  whey,  and  also  the  amount  of  solids  not  fat, 
is  increased. 

While  milk  is  always  free  of  nitrates  and  nitrites, 
even  if  the  animals  have  taken  such  substances  with 


222  MILK  HYGIENE 

their  food,  these  are  frequently  present  in  water  in  small 
quantity.  The  presence  of  nitrates  or  nitrites  in  the 
milk,  therefore,  shows,  with  certainty,  that  water  has 
been  added.  However,  the  lack  of  nitrates  does  not  ex- 
clude this,  as  all  water  does  not  contain  nitrates.  Even 
a  very  small  quantity  of  nitrates  and  nitrites  can  be 
detected  as  follows : 

1.5  e.c.  of  a  20  per  cent,  calcium  chloride  solution  is  added  to 
100  c.c.  of  milk;  the  mixture  is  boiled  and  filtered.  A  little  of  the 
filtrate  is  mixed  with  enough  of  a  2  per  cent,  solution  of  diphenylamin 
in  sulphuric  acid  to  make  it  milky;  a  little  concentrated  sulphuric  acid 
is  poured  into  a  test  tube  and  the  mixture  is  added  slowly,  so  that 
the  fluids  do  not  mix;  if  nitric  acid  or  nitrous  acid  is  present,  a  blue 
zone  is  formed  at  the  plane  of  contact.  (Soxhlet.) 

[A  simpler  test  for  nitrates  is  that  devised  by  Richmond.  The 
following  description  of  this  test  is  from  Farrington  and  Woll.55 
"  Place  a  small  quantity  of  diphenylamin  at  the  bottom  of  a  porcelain 
dish,  and  add  to  it  about  1  c.c.  of  pure,  concentrated  sulphuric  acid; 
allow  a  few  drops  of  the  milk  serum  (obtained  by  adding  a  little 
acetic  acid  to  the  milk  and  warming)  to  flow  down  the  sides  of 
the  dish  and  over  the  surface  of  the  acid.  If  a  blue  color  develops  in 
the  course  of  ten  minutes,  though  it  may  be  faint,  it  shows  the 
presence  of  nitrates,  after  ten  minutes  a  reddish-brown  color  is 
always  developed  from  the  action  of  the  acid  on  the  serum.  There 
should  be  no  difficulty  in  detecting  an  addition  of  10  per  cent,  of 
water  to  the  milk  by  this,  test,  if  the  water  added  contained  5  parts 
of  nitric  acid,  or  more,  per  100,000."  L.  P.] 

c.  The  skimming  of  whole  milk  in  conjunction  with 
the  addition  of  water,  or  the  addition  of  skimmed  milk 
as  well  as  water,  are  common  methods  of  adulteration. 
It  is  easily  understood  that  the  fat  content  is  consid- 
erably lessened  in  this  way,  and  that  also  the  solids  not 
fat  decrease ;  it  is  evident,  besides,  that  the  percentage 
of  solids  not  fat  (p)  is  lessened  and,  consequently,  the 

55  Farrington  and  Woll.  Testing  Milk  and  its  Products,  13th 
edition.  Madison,  1904. 


DETECTION    OF    ADULTERATION        223 

specific  gravity  of  the  solids  (m)  must  be  increased.  The 
specific  gravity  of  adulterated  milk  can  vary  consider- 
ably, often  it  is  nearly  normal,  but  frequently  it  is 
slightly  diminished.  Feser  has  given  the  following  ex- 
ample of  such  adulteration : 

The  unadulterated  milk  had  3.95  per  cent.,  fat;  8.9 
per  cent.,  solids  not  fat;  1.031  specific  gravity;  by  par- 
tial skimming,  it  was  changed  to  2.19  per  cent.,  fat; 
about  8.9  per  cent.,  solids  not  fat ;  1.034,  specific  gravity ; 
by  the  addition  of  water  it  was  further  changed  to  1.21 
per  cent.,  fat;  about  8  per  cent.,  fat  free  solids;  1.0305, 
specific  gravity. 

Decisive  points  for  determining  if  such  adulterations 
exist  are  the  low  solid  contents,  the  low  fat  per  cent., 
the  almost  normal  specific  gravity  of  the  milk,  the  in- 
creased specific  gravity  of  the  solids  (m)  which,  in  the 
above  example,  was  changed  from  1.305  to  1.473,  and  in 
the  low  specific  gravity  of  the  whey.  If  nitrates  are 
proven  in  the  milk  there  is  further  support  for  the  con- 
clusion that  it  is  watered. 

When  a  sample  of  adulterated  milk  can  fairly  be 
compared  with  another  which  is  known  to  be  unadulter- 
ated (samples  taken  from  the  same  dealer  the  same  day, 
milk  of  a  large  herd,  etc.)  [or  with  an  accepted  stand- 
ard] one  can  form  an  opinion  of  the  extent  of  the 
adulteration  by  means  of  a  formula  derived  from  Bohm- 
lander : 

M=--?x  w  — w 


E  ==  100 


(-£) 


M  shows  the  quantity  of  water  added  to  100  grm.  of 
rnilk;  "VV  is  the  per  cent,  of  water  in  the  unadulterated 
and  w  in  the  adulterated,  or  suspected,  sample ;  R  and  r 
are  the  percentages  in  these  two  samples  of  solids  not 


224 


MILK  HYGIENE 


fat;  E  represents  the  percentages  of  fat  removed  by 
skimming,  while  F  and  f  show  the  percentage  of  fat  in 
the  two  samples. 

In  the  above  case  one  could  find  by  computation: 


90.79  -f-  87.15  =  1.112  X  90.79  —  87.15  =  13.81 


E  -  100 

0 


(\        L21  X  8  9>\   -     100  (^ 

V1    '  UslTsV  V   " 


=  66 


Or,  in  other  words,  about  14  grin,  of  water  are  added 
to  each  100  grm.  of  milk  and  about  66  grm.  of  fat  have 
been  taken  from  each  100  grm.  of  fat. 

The  effects  of  the  various  adulterations  may  be 
shown  in  tabular  form  as  follows  :* 


o, 

>, 

. 

- 

3 

>  a? 

0 

0.2 

"8 

«*_• 

61 

II 

f*a 

|1 

0)  0 

| 

%°  . 

O  0) 

en 

•^   »-H   02 

-H 

rj   S  -2> 

2^ 

a 

Si2 

S^S 

S'^s 

§  * 

C3   §  g 

0 

o.'o 

^3! 

11 

i.o's 

§21 

i'l 

g'S'S 

cc 

cc 

PH 

PH 

CO 

Pt 

PH 

A^ 

f 

1.029  to 

Normal  milk  J 

1.034 

1.029  to 

3  to  5 

8.5  to 

1.30  to 

20  to 

0.7  to 

aver. 

1.031 

10.5 

1.34 

34 

0.75 

1 

1.032 

Skimmed  or  diluted    f 
with  skimmed  milk  -\ 

higher 

no 
change 

lower 

very 
slightly 
higher 

higher 

lower 

higher 

0 

Water  added  j 

Skimmed  and 
water  added  J 

lower 

little 
change 

lower 
lower 

lower 
lower 

lower 
lower 

no 
change 

higher 

no 
change 

lower 

lower 
lower 

+  orO 
+  orO 

Although  each  form  of  adulteration  has  its  own  char- 
acteristics yet,  in  practice,  it  is  often  very  hard  to  deter- 
mine whether  a  slight  adulteration  has  occurred,  be- 
cause the  composition  of  milk,  as  explained  above,  dif- 
fers so  much  physiologically — and  with  the  same  animal 
from  day  to  day.  Unless  there  is  a  distinct  departure 
from  the  normal,  one  should  be  careful  in  expressing 
his  opinion,  especially  if  he  does  not  know  the  herd  con- 


*This  table  is  changed  somewhat  from  the  one  prepared  by  Jensen  [L.  P.] 


DETECTION    OF    ADULTERATION        225 

cerned.  Usually,  the  presence  of  nitrates  is  positive, 
still  it  must  not  be  forgotten  that  when  the  milk  can  is 
rinsed  a  little  water  may  be  left,  which,  if  it  is  rich  in 
nitrates,  may  cause  the  milk  to  show  a  slight  reaction, 
so  that  it  might  appear  that  water  has  been  intentionally 
added.  Usually  water  does  not  contain  such  a  quantity 
of  nitrates  as  to  cause  a  suspicious  reaction  when  the 
milk  has  not  really  been  adulterated.  ; 

d.  Adulteration     of     partly     skimmed     and     skimmed 
milk.    In  most  cities  no  minimum  limit  is  fixed  for  the 
fat  content  of  the  half  skimmed  and  the  skimmed  milk, 
and  the  only  form  of  adulteration  to  be  considered  in 
this  connection  is  the  addition  of  water.    This  causes  a 
lowering  of  the  specific  gravity  of  the  milk  (from  1.030 
to  1.036  to  from  1.032  to  1.040)  and  whey,  as  well  as  a 
diminution  in  the  amount  of  solids.    A  possible  trace  of 
nitrates  proves  that  the  milk  has  been  watered.     In 
cities,  in  which  the  minimum  limit  of  fat  content  for 
partially  skimmed  milk  or  skimmed  milk  has  been  es- 
tablished, the  milk  is,  of  course,  considered  adulterated 
when  it  falls  below  this  standard.    [In  some  places  there 
is  a  standard  of  9.25  per  cent,  total  solids  for  skimmed 
milk  as  provided  by  the  U.  S.  Department  of  Agricul- 
ture.] 

e.  Adulteration  of  cream.    Cream  is  sold  in  different 
forms,  with  fat  content  varying  between  about  10  per 
cent,  and  30  per  cent.  (40  per  cent.).    In  some  cities,  the 
minimum  content  of  different  grades  is  defined,  so  in 
such  cases  public  control  must  be  extended  to  determin- 
ing the  amount  of  fat  in  cream.    Of  the  different  aduL 
terations,  the  addition  of  starch  and  flour  are  to  be 
mentioned  particularly.    This  is  done  to  make  the  cream 
thicker  and  to  give  it  the  appearance  of  being  better 
than  it  really  is.     In  raw  cream,  the  proof  by  micro- 
scopic examination  is  simple,  as  the  starch  grains  are 

15 


226  MILK  HYGIENE 

shown  as  irregular,  round  concentrically  formed  bodies. 
Amyloid  bodies  have  been  found  in  milk  by  Herz ;  these 
are  like  similar  bodies  previously  found  in  the  pros- 
tates, and  somewhat  resemble  starch  grains,  but  are 
hardly  to  be  found  in  such  great  quantity  that,  in  prac- 
tice, they  have  any  influence  on  this  examination.  After 
the  cream  is  boiled,  the  starch  grains  burst,  and  cannot 
be  recognized  under  the  microscope.  In  this  case,  the 
chemical  test  must  be  applied,  which  may  be  used  with 
raw  cream  also.  The  simple  addition  of  a  diluted  solu- 
tion of  iodine,  in  many  cases,  gives  the  milk  the  well- 
known  blue  color;  it  is  better,  however,  to  add  a  little 
acetic  acid,  boil  and  filter  and  apply  the  iodine  test  to 
the  filtrate.  [The  presence  of  "viscogen"  is  indicated 
by  the  greater  percentage  of  ash.] 

The  detection  of  other  foreign  substances,  as  white 
earth,  emulsion  of  brain  substance,  etc.,  is  best  made  by 
means  of  microscopic  examination. 

VI.     PUBLIC  SUPERVISION  TO   PREVENT  THE  SALE  OF 
DETERIORATED   MILK 

The  public  should  not  only  make  and  enforce  regula- 
tions regarding  the  production  and  handling  of  milk  to 
prevent  adulteration,  but  it  should  make  regulations  to 
prevent  milk  being  sold  in  a  damaged  or  spoiled  con- 
dition and,  by  frequent  inspection,  these  regulations 
should  be  enforced.  The  milk  samples  that  are  taken 
must  not  only  be  used  for  the  purpose  of  determining 
possible  falsification  but,  at  the  same  time,  they  should 
be  subjected  to  a  number  of  other  examinations. 

a.  Determination  of  the  appearance,  odor  and  taste.  All 
milk  differing  from  normal  in  color  or  appearance  (mix- 
ture of  blood  or  exudate,  abnormal  secretion,  secretion 
of  coloring  matter,  bacterial  alterations),  or  by  odor  or 
taste  (abnormal  composition,  the  excretion  of  odorifer- 


DETECTION  OF  DETERIORATION        227 

ous  substances,  absorption  of  strongly  odorous  matter, 
addition  of  foreign  matter,  bitter,  stale,  sour,  microbic 
changes)  must  not  be  sold  and  should  be  condemned. 

b.  Determination  of  the  reaction.  This  may  be  done  by 
using  red  and  blue  litmus  paper.  Normal,  quite  fresh 
milk  has  an  amphoteric  reaction.  If  the  test  shows  ex- 
cessive alkaline  or  acid  reaction,  it  should  be  examined 
more  closely.  An  alkaline  reaction  is  frequently  shown 
in  the  milk  of  old  milking  cows;  mixed  milk,  on  the 
contrary,  is  never  alkaline.  Sometimes  an  alkali  is 
added;  if  so,  it  can  be  proven  by  the  test  previously 
mentioned,  or,  quite  easily,  by  titrating  with  tenth- 
normal  sodium  hydrate  solution,  with  which  phenol- 
phthalin  is  used  as  indicator.  Normal  milk  shows  an 
acid  reaction  to  phenolphthalin,  so  that  from  18  to  19 
c.c.  of  tenth-normal  sodium  hydrate  solution  must  be 
added  to  100  c.c.  of  milk  to  make  the  red  color  appear ; 
if  the  milk  becomes  red  at  once  when  phenolphthalin  is 
added,  then  it  is  abnormally  alkaline  and,  as  a  rule,  alkali 
has  been  added ;  if  a  smaller  quantity  of  sodium  hydrate 
solution  is  necessary,  the  milk  may  either  have  been 
treated  with  alkali  or  diluted  with  water. 

If  the  litmus  paper  indicates  an  acid  reaction,  the 
degree  of  acidity  of  the  milk  may  be  determined  by 
means  of  titrating  with  tenth-normal  solution  of  so- 
dium hydrate,  using  phenolphthalin  as  indicator.  If,  to 
neutralize  100  c.c.,  requires  more  than  18  to  19  c.c.  of 
tenth-normal  sodium  hydrate  solution,  then  the  for- 
mation of  lactic  acid  has  commenced,  and  its  extent  can 
be  measured  exactly  by  determining  the  amount  of 
standard  alkali  required  to  neutralize  it. 

For  titrating,  an  ordinary  burette  is  used  with  a  scale 
divided  into  spaces  showing  0.1  c.c.  After  the  addition 
of  about  0.25  c.c.  phenolphthalin  solution  to  the  milk,  the 
standard  sodium  solution  is  dropped  in,  little  by  little, 


228  MILK  HYGIENE 

until,  after  thorough  shaking,  the  milk  becomes  faintly 
reddish.  Then  the  exact  amount  of  solution  that  has 
been  used  for  neutralization  is  read  off,  and  the  degree 
of  acidity  determined.  If  one  has  to  make  many  titra- 
tions  it  is  most  convenient  to  use  a  burette  with  a  supply 
from  a  larger  tank;  such  a  titrating  apparatus  can  be 
procured  from  any  dealer  in  chemical  apparatus. 

[A  rapid  method  for  determining  the  acidity  of  milk 
has  been  devised,  which  depends  on  the  use  of  an  accu- 
rately measured  amount  of  alkali  dispensed  in  the  form 
of  a  tablet.  This  makes  it  possible  to  quickly  prepare  a 
standard  solution,  and  the  method  is  very  useful  for  in- 
spections in  the  field.  If  the  indicator,  phenolphthalin, 
is  included  in  the  tablet,  the  test  is  still  more  convenient. 
It  is  made  as  follows : 

Tablets  are  dissolved  in  a  measured  quantity  of  dis- 
tilled water,  sufficient  to  give  a  solution  of  standard 
strength  (usually  five  tablets  make  100  c.c.  of  solution, 
but  this  varies  with  the  brand  of  tablet  and  the  manu- 
facturer's instructions  must  be  observed)  18  grm.  (17.6 
c.c.,  being  measured  in  the  pipette  used  for  the  Babcock 
test)  of  milk  are  measured  into  a  white  porcelain  cup 
and  the  alkali  solution  is  added  from  a  measure  (burette 
or  graduated  cylinder)  until  the  pink  color  becomes 
permanent.  The  amount  of  solution  used  shows  the 
percentage  of  acid  in  the  sample. 

If  a  standard  of  0.2  per  cent,  lactic  acid  has  been 
adopted,  then  the  amount  of  alkali  solution  required  to 
show  any  excess  above  this  limit  may  be  placed  directly 
in  the  cup  and  the  measured  sample  of  milk  added  to  it. 
If  the  pink  color  remains,  there  is  less  than  0.2  per  cent, 
of  acid  in  the  sample;  if  it  disappears,  there  is  more 
than  0.2  per  cent,  of  acid.  L.  P.] 

Only  a  few  German  regulations  give  a  standard  for 
the  acid  permitted  in  market  milk.  Sometimes,  the 


THE  FERMENTATION  TEST  229 

requirement  is  made  that  the  milk  shall  withstand  the 
test  of  boiling  it  in  a  test  tube  without  the  separation  of 
flakes  or  curds,  and  be  able  to  withstand  the,  so-called, 
alcohol  test,  which  is  made  as  follows : 56 

Exactly  equal  parts  of  milk  and  alcohol  (68  per  cent.) 
are  carefully  mixed  in  a  tube  and  observed  closely. 
Fresh  milk  shows  no  precipitation ;  in  that  which  is  be- 
ginning to  sour,  fine  flocules  are  deposited  on  the  walls 
of  the  glass  and,  with  greater  acidity,  flakes  and  lumps 
are  separated. 

c.  The  fermentation  test  is  used  to  show  whether  there 
is  an  excess  of  bacteria  of  putrefaction  in  the  milk.  It 
consists  simply  in  incubating  a  sample  of  milk  at  body 
temperature  for  8  to  16  hours,  followed  by  an  examina- 
tion as  to  its  appearance,  odor  and  flavor.  The  examina- 
tion is  easily  made  as  follows:  Into  large  test  tubes 
holding  at  least  25  c.c.,  that  have  been  carefully  cleaned 
and  sterilized,  the  milk  samples,  warmed  to  about  36°  C. 
(97°  F.),  are  poured.  The  tubes  are  closed  by  cotton 
and  placed  in  an  incubator  or  closet,  where  they  are  kept 
at  30°  to  35°  C.  (86°  to  95°  F.).  In  the  course  of  eight 
or  ten  hours,  and  again  later,  the  contents  of  the  tubes 
are  examined.  Good,  undeteriorated  milk  is  then  sour 
and  curdled  and  forms  a  homogeneous  coagulum,  without 
much  separation  of  whey  or  formation  of  gas.  Fre- 
quently, gas  bubbles  have  split  the  coagulum  and  con- 
siderable fluid  has  separated.  This  change,  however, 
does  not  necessarily  signify  that  the  milk  was  particu- 
larly rich  in  bacteria  of  putrefaction.  On  the  other 
hand,  if  the  milk  curdles  and  has  an  offensive  odor,  or 

56  As  a  result  of  boiling,  separation  occurs  not  only  where  the 
milk  has  reached  a  certain  degree  of  acidity  but  also  in  cases  where, 
as  a  result  of  disease  of  the  cow,  abnormally  large  quantities  of 
albumin  and  of  globulin  are  present,  or  when  there  is  admixture  of 
colostrum. 


230  MILK  HYGIENE 

if  the  coagulum  is  beginning  to  dissolve,  or  if  the  milk 
remains  in  a  fluid  state  but  has  a  bad  odor  and  taste, 
these  are  signs  that  the  milk  is  contaminated  with  bac- 
teria of  putrefaction.  In  the  application  of  this  test,  it 
is  important  not  to  allow  the  milk  sample  to  stand  too 
long  before  the  examination  is  begun,  and  precautions 
must  be  taken  to  prevent  contamination  while  gathering 
the  sample  and  during  the  test. 

In  pasteurized  milk,  the  fermentation  test  may  give 
general  information  concerning  the  bacterial  content, 
through  noting  the  time  that  passes  until  appreciable 
changes  take  place.  Usually  such  milk  does  not 
' '  sour. ' '  But  no  precipitate  conclusion  should  be  drawn 
from  the  results  of  this  test. 

By  boiling  the  milk  for  a  short  time  and  then  incu- 
bating the  samples,  a  serviceable  guide  can  be  obtained 
concerning  the  quantity  of  the  spore  bearing  bacteria 
in  the  milk.  These  will  survive  the  heating,  and,  as  they 
are  not  checked  in  their  growth  by  the  lactic  acid  form- 
ing bacteria,  they  increase  rapidly  and  cause  the  milk  to 
curdle,  by  the  action  of  ferments. 

[Eussell 57  describes  a  curd  fermentation  test  used  by 
cheese  makers,  as  follows:  "  When  the  milk  is  95°  F., 
about  10  drops  of  rennet  extract  are  added  to  each  sam- 
ple and  mixed  thoroughly  with  the  milk.  The  jar  should 
then  remain  undisturbed  until  the  milk  is  completely 
curdled;  then  the  curd  is  cut  into  small  pieces  with  a 
case  knife  and  stirred,  to  expel  the  whey.  The  whey 
should  be  poured  off  at  frequent  intervals  until  the  curd 
mats.  If  the  sample  be  kept  at  blood  heat  (98°  F.),  for 
six  to  eight  hours,  it  will  be  ready  to  examine. 

"  The  curd  from  a  good  milk  has  a  firm,  solid  tex- 

57  H.  L.  Russell,  Dairy  Bacteriology,  Sixth  Edition.  Madison, 
1905. 


BACTERIOLOGICAL  EXAMINATIONS      231 

ture,  and  should  contain  at  most  only  a  few  small  '  pin  ' 
holes.  It  may  have  some  large,  irregular  '  mechan- 
ical '  holes  where  the  curd  particles  have  failed  to  ce- 
ment. If  gas-producing  bacteria  are  very  prevalent  in 
the  milk,  the  conditions  under  which  the  test  is  made 
cause  such  a  rapid  growth  of  the  same  that  the  evidence 
of  the  abnormal  fermentation  may  be  readily  seen  in  the 
spongy  texture  of  the  curd.  If  the  undesirable  organ- 
isms are  not  very  abundant  and  the  conditions  are  not 
especially  suited  to  their  growth,  the  '  pin  '  holes  will 
be  less  frequent. 

i  i  Sometimes  the  curds  show  no  evidence  of  gas,  but 
their  abnormal  condition  may  be  recognized  by  the 
'  mushy  '  texture  and  the  presence  of  '  off  '  flavors, 
that  are  rendered  more  apparent  by  keeping  them  in 
closed  bottles.  This  condition  is  abnormal  and  is  apt  to 
produce  quite  as  serious  results  as  if  gas  was  formed." 

Curd  fermentation  tests  have  been  suggested  for  use 
in  connection  with  the  supervision  of  market  milk,  and 
C.  E.  Marshall  has  made  some  observations  that  tend 
to  show  their  usefulness  for  this  purpose.  L.  P.] 

To  make  regulations  in  relation  to  the  behavior  of 
milk  to  these  tests  would  be  premature.  The  general 
requirement  that  market  milk,  aad  especially  infants' 
milk,  shall  not  be  rich  in  bacteria  of  putrefaction  is  suf- 
ficient for  the  present. 

d.  Bacteriological  examinations  are  made  when  more 
information  is  desired  regarding  the  number  and  kind  of 
bacteria  in  milk.  As  has  been  said,  this  differs  greatly, 
even  in  freshly  drawn  milk,  and  it  is  scarcely  possible 
to  state  a  passing  average  for  the  bacterial  content  of 
market  milk.  Nor  does  it  seem  to  be  possible  to  estab- 
lish a  maximum  by  ordinance,  the  violation  of  which 
would  lead  to  the  condemnation  of  the  milk.  Yet,  it  is 
of  importance  to  health  officers  to  have  an  examination 
made  of  the  number  of  bacteria  in  milk  sold,  since,  by 


232  MILK  HYGIENE 

so  doing,  an  opinion  can  be  formed  as  to  the  genuine- 
ness of  the  claims  of  the  milk  companies,  as  well  as  the 
cleanliness  and  care  with  which  the  milk  has  been  han- 
dled from  the  time  it  was  drawn  until  it  was  sold.  There 
are  special  reasons  for  making  regular  bacteriological 
examinations  of  nursery  milk;  it  must  be  required  not 
only  that  this  shall  come  from  healthy  animals  and  not 
be  exposed  to  infection  with  pathogenic  bacteria,  but, 
at  the  same  time,  it  is  well  to  require  that  it  shall  not 
contain  an  excess  of  bacteria  at  the  time  it  is  delivered 
to  customers.  In  this  connection,  it  would  be  very  ad- 
vantageous to  make  a  stipulation  to  the  effect  that  ves- 
sels [bottles]  in  which  infants'  milk  is  sold  shall  be  pro- 
vided with  a  label  giving  the  day  on  which  the  milk  was 
produced.  A  bacteriological  examination  of  infants' 
milk  is  of  importance  as  indicating  the  thoroughness  and 
effectiveness  of  the  methods  of  the  concern  and  as  indi- 
cating the  need,  perhaps,  of  subjecting  these  methods  to 
tliorough  revision. 

There  are  other  reasons  for  establishing  a  bacterio- 
logical examination  of  pasteurized  (and  sterilized)  milk, 
since,  in  this  way,  most  important  information  may  be 
gained  concerning  the  reliability  or  the  inefficiency  of 
the  methods  in  use  by  the  various  concerns.  It  would 
also  be  of  advantage,  in  connection  with  this  inspection, 
to  require  that  the  containers  of  pasteurized  milk  shall 
be  marked  with  a  tag  showing  the  day  and  method  of 
pasteurization  (or  sterilization). 

The  counting  of  bacteria  in  milk  is  not  a  difficult 
matter,  but  when  many  samples  are  to  be  examined  in 
this  way  much  time  is  required.  The  method  is,  in  gen- 
eral, the  same  as  that  used  for  estimating  the  number 
of  bacteria  in  water  or  other  fluids  ( see  the  text-books  on 
bacteriology).  It  is  best  to  use  gelatin  that  has  been 
made  with  milk.  A  good  way  is  to  add  100  grms.  of  gel  a- 


BACTERIOLOGICAL  EXAMINATIONS      233 

tin  to  one  liter  of  milk,  boil,  filter,  neutralize,  boil  and 
filter  again.  Or,  one  can  use  agar-agar  in  place  of  gela- 
tin in  making  this  culture  medium.  In  this  case,  it  is 
necessary  to  first  remove  the  casein  by  the  use  of  ren- 
net. By  this  method,  one  may  obtain  agar  or  gelatin 
that  is  fairly  transparent.  The  culture  media  should  be 
placed  in  test  tubes  in  the  usual  way.  The  examination 
can  be  made  as  follows:  By  the  use  of  an  ordinary 
cover  glass  preparation,  examined  under  the  microscope, 
one  ascertains  whether  the  milk  is  especially  rich  in  bac- 
teria. If  there  are  only  a  few  bacteria,  usually  three  gel- 
atin tubes  will  suffice,  otherwise  four  or  five  must  be  used. 
One  c.c.  of  milk  is  measured  out  and  is  mixed  with  9  c.c. 
of  fluid  gelatin  in  a  test  tube.  After  mixing,  one  c.c. 
of  the  mixture  is  placed  in  another  tube  containing  9  c.c. 
of  fluid  gelatin.  From  this  mixture  a  third  tube  is  inoc- 
ulated, and  so  on.  In  this  way  different  dilutions  of  milk 
are  obtained.  Tube  no.  1  contains  0.9  c.c.  of  milk; 
no.  2,  0.09;  no.  3,  0.009;  no.  4,  0.0009;  no.  5,  0.0001.  If 
nothing  is  taken  out  of  tubes  2,  3  and  4  for  the  purpose 
of  making  further  dilutions,  they  contain  0.1,  0.01  and 
0.001  c.c.  of  milk.  Of  course  one  can  make  mixtures  in 
any  other  desired  proportion. 

After  making  the  proper  dilutions  the  fluid  is  poured 
in  a  Petri  dish  which,  of  course,  must  have  been  steril- 
ized. After  the  mass  of  gelatin  becomes  firm,  the  covered 
dish  is  put  away  and  is  kept  at  an  appropriate  tempera- 
ture. In  the  course  of  time  more  or  less  colonies  form 
on  the  gelatin,  these  are  counted  on  the  whole  plate  or 
on  a  definite  sub-division,  and  by  this  means  the  approx- 
imate number  of  bacteria  in  one  c.c.  of  milk  may  be 
estimated.  The  result  of  the  count  is  by  no  means  exact 
for  a  number  of  reasons,  but  this  method  gives  an 
approximation  that  is  sufficient  for  practical  purposes. 
[The  milk  may  be  diluted  with  water  instead  of  being 


234  MILK  HYGIENE 

diluted  through  the  gelatin  tubes.  Agar-agar  is  pre- 
ferred to  gelatin  because  it  can  be  used  for  plates  to  be 
incubated.  If  comparative  counts  are  to  be  made  the 
apparatus  and  temperatures  of  incubation  and  the  char- 
acter of  culture  media  should  be  the  same.  Porous 
Petri  dish  covers  are  preferred  to  glass  covers  because 
they  tend  to  prevent  spreading  colonies.  For  a  descrip- 
tion of  the  method  used  in  the  bacteriological  examina- 
tion of  milk  in  the  laboratory  of  the  Boston  Board  of 
Health  see  a  paper  by  Slack  in  the  Journal  of  Infectious 
Diseases,  Supplement  No.  2,  February,  1906.  L.  P.] 

The  detection  of  specific  pathogenic  bacteria  is  so 
difficult  and  the  examination  gives  such  unreliable  re- 
sults that  practically  it  is  not  worth  while  to  search  for 
them.  The  bacteria  of  typhoid  fever  and  diphtheria  have 
rarely  been  discovered  through  the  use  of  cultural  meth- 
ods ;  the  tubercle  bacillus  may  sometimes  be  discovered 
under  the  microscope  but  usually  it  is  present  in  such 
small  amounts  that  it  cannot  be  detected.  The  best  way 
to  examine  milk  for  tubercle  bacilli  is  by  inoculation  of 
experimental  animals.  A  conclusion,  however,  cannot 
be  drawn  from  this  experiment  until  one  or  two  months 
have  elapsed. 

e.  [Examination  for  pus.  The  examination  of  milk  for 
pus  was  first  suggested  by  Dr.  Stokes,  of  Baltimore, 
and  has  since  been  carried  out  in  a  number  of  public 
health  laboratories  in  different  parts  of  the  United 
States.  The  researches  of  Stokes,  Bergey,  Stewart, 
Doane,  Slack,  and  others  have  shown  that  cells  are  pres- 
ent in  practically  all  samples  of  milk  and  that  in  some 
samples  the  cellular  content  is  much  higher  than  is  usual. 
Where  the  number  of  cells  is  high  it  is  customary  to 
regard  them  as  pus  cells,  but  there  is  no  general  agree- 
ment as  to  where  the  line  should  be  drawn.  The  question 
is  a  difficult  one  because  pus  cells  and  dead  leucocytes 


EXAMINATION  FOE  DIRT  235 

are  morphologically  the  same  and  so  can  not  be  differ- 
entiated by  their  appearance  alone.  .  Doane  has  pro- 
posed that  milk  shall  be  regarded  as  containing  pus  if 
there  is  high  cellular  content  accompanied  by  threads 
of  fibrin.  Bergey  proposes  that  pus  shall  be  diagnosed 
if  there  are  10  cells  to  the  field  of  the  1/12  immersion 
lens.  Stewart  centrifuges  1  c.c.  of  milk  in  small  tubes 
and  if  he  find  23  cells  to  the  field  of  the  1/12  immersion 
lens,  when  the  sediment  of  this  amount  of  milk  is  spread 
over  1  square  cm.,  he  reports  pus.  Slack  proposes  that 
the  sediment  of  2  c.c  milk  shall  be  spread  over  4  square 
cm.  and  that  pus  shall  be  reported  if  50  cells  are  seen 
to  the  1/12  immersion  field. 

Since  there  is  much  doubt,  in  many  cases,  as  to 
whether  high  cellular  content  actually  denotes  pus, — that 
is,  as  to  whether  the  cells  found  are  pus  cells  or  leuco- 
cytes, and  as  to  whether  the  cells  themselves  are  in- 
jurious, it  would  appear  to  be  desirable,  for  the  present, 
to  report  pus  only  where  there  is  high  cellular  content, 
as  judged  by  one  of  the  above  methods,  accompanied  by 
the  presence  of  streptococci.  L.  P.] 

/.  Examination  for  dirt.  The  sale  of  unclean  or  dirty 
milk  should  be  forbidden.  A  number  of  cities  in  Ger- 
many have  established  the  requirement  that  milk  shall 
not  contain  over  a  definite  amount  of  dirt ;  the  limit  va- 
ries from  5  to  10  milligrams  of  dry  dirt  to  a  liter  of  milk. 
An  examination  for  dirt  can  be  made  as  follows :  The 
milk  is  placed  in  bottles,  which  are  centrifuged,  the  milk 
is  decanted  and  the  sediment  is  dried  at  a  temperature  a 
little  above  that  of  boiling  water.  This  material  is 
weighed  and  its  quantity  per  liter  is  calculated. 

Instead  of  this  rather  formidable  method  it  is  usu- 
ally sufficient  to  centrifuge  the  milk  and  then  measure 
the  sediment.  Or,  one  can  pour  the  milk  in  a  high  glass 
of  conical  shape  and  ascertain  the  amount  of  sediment 


236 


MILK  HYGIENE 


that  collects  in  a  given  time.  Gerber  lias  constructed  a 
special  apparatus  for  this  purpose  by  means  of  which  a 
fair  approximation  of  the  amount  of  dirt  in  milk  can  be 
made  by  simply  measuring  it. 

Generally,  the  only  requirement  on  this  point  is  that 
market  milk  shall  not  deposit  visible  sediment  upon 
standing  for  two  hours.  [An  apparatus  for  this  purpose 
has  also  been  devised  by  Otto,  which  can  easily  be  under- 
stood by  the  accompanying  figure.  The  bottle,  A,  which 
contains  the  milk  is  open  at  each  end.  The  mouth  of  the 
bottle  must  be  closed  by  a  cork  held  upon  a  rod,  C.  A 


FIG.  24. 


O 


9 


Otto's  apparatus  for  estimating  dirt  in  milk. 

fine  tube,  B,  with  a  still  finer  point  and  closed  at  the  thin 
end,  is  attached  to  the  mouth  of  the  bottle  by  a  short 
rubber  tube  after  which  the  cork  on  the  rod  C  is  with- 
drawn. The  milk  is  then  permitted  to  stand  in  this 
container,  held  in  a  rack,  for  a  given  time.  At  the  end 
of  this  time,  the  stopper  is  replaced  in  the  mouth  of 
the  bottle,  the  small  tube  is  detached  and  the  amount 


THE     "       X 

UNIVERSITY    ) 
OF  / 

RN^X 
EXAMINATION  FOKPKfeSEEVATIVES    237 

of  dirt  is  read  from  the  scale.  Stewart  lias  devised  a 
method  that  gives  good  results  in  the  laboratory  of  the 
Board  of  Health  in  Philadelphia.  It  consists  in  the  use 
of  small  glass  tubes,  open  at  each  end;  the  lower  open- 
ing is  closed  with  a  small  rubber  stopper.  The  tubes 
are  filled  with  milk,  and  are  centrifuged.  The  dirt  is 
thrown  upon  the  rubber  stopper  and  adheres  thereto 
when  the  stopper  is  withdrawn.  It  may  easily  be  trans- 
ferred to  a  slide  for  microscopic  examination.  Pus  cells 
are  collected  in  the  same  way.  L.  P.] 

g.  Examination  for  preservatives.  One  of  the  most  im- 
portant regulations  with  regard  to  the  milk  trade  is 
that  milk  shall  not  be  preserved  by  the  use  of  antiseptics 
or  alkalies,  and  one  of  the  most  important  functions  of 
the  milk  inspector  is  to  see  that  this  regulation  is  ob- 
served. An  occasional  test  for  preservatives  may  be 
made  by  standing  the  samples  aside  at  room  tempera- 
ture. If  the  milk  does  not  change  within  the  time  that  is 
customary  for  good  milk,  the  presence  of  artificial  pre- 
servatives may  be  suspected.  Methods  for  the  detec- 
tion of  preservatives  by  chemical  means  have  already 
been  given. 

If  the  increased  keeping  power  of  the  milk  is  due  to 
the  addition  of  alkalies,  this  may  be  indicated  by  a  simple 
test  with  litmus  paper. 


APPENDIX   I. 

THE  REGULATIONS  GOVERNING  THE  TRI- 

FOLIUM    MILK   SUPPLY   COMPANY 

IN  COPENHAGEN,  DENMARK. 

I.  THE    WORK    OF    THE    COMPANY    SHALL    BE    UNDER    THE    SUPER- 

VISION   OF    A    COMMITTEE    OF    CONTROL    CONSISTING    OF    A 
PHYSICIAN  AND  A  VETERINARIAN. 

II.  THE  OBLIGATIONS  OF  THE  COMPANY    TO    THE    COMMITTEE    OF 

CONTROL  SHALL  BE  AS  FOLLOWS. 

1.  Milk  may  be  taken  only  from  herds  that  have  been  ap- 
proved by  the  committee,  and  that  furnish  milk  containing  at 
least  3  per  cent.  fat. 

2.  Nursery   (children's)   milk  shall  come  only  from  herds 
that  are  proven  to  be  entirely  free  from  tuberculosis  by  the 
use  of  the  tuberculin  test,  and  these  herds  shall  be  retested  at 
least  once  a  year.     Milk  may  be  received  from  a  tuberculosis- 
free  part  of  a  herd  only  after  the  committee  has  investigated 
the  conditions,  and  has  given  its  approval.     In  this  case,  the 
healthy  part  of  the  herd  is  to  be  kept  entirely  apart  from 
the  reacting  section,  it  is  to  be  retested  at  least  once  a  year, 
and  the  reacting  animals  are  gradually  to  be  disposed  of. 

If  a  calf  plague  (calf  cholera,  contagious  pneumonia, 
pyaemia,  etc.)  occurs  in  the  herd  the  committee  may  require 
shipments  of  milk  to  be  discontinued  until  further  notice. 

3.  The  company  pays  one  or  more  veterinarians,  who  are  ap- 
pointed by  and  are  responsible  to  the  committee  of  control. 

Farms  that  supply  the  regular  whole  milk,  skimmed  milk 
and  cream  are  to  be  inspected  by  the  veterinarian  twice  a 
month,  unless  in  summer  the  cows  are  kept  stabled,  in  which 
case  four  visits  per  month  are  to  be  made.  Herds  that  supply 
nursery  milk  are  to  be  inspected  the  year  through  four  times  a 
month.  Travelling  expenses  are  paid  by  the  company. 

4.  Nursery  milk  is  to  be  shipped  only  in  containers  that 

239 


240  MILK  HYGIENE 

are   easily   distinguished  by  their  shape   and   color  from   the 
containers  used  for  the  regular  milk. 

5.  The  company  shall  not  employ  any  weakly  persons,  nor 
any  that  are  afflicted  with  an  infectious  disease  or  with  any 
repulsive  skin  disease,  as  tuberculosis  or  syphilis.     Any  em- 
ployee so  affected  is  to  be  dismissed. 

If  any  one  of  the  employees  shall  contract  typhoid  fever, 
gastric  fever,  diphtheria,  scarlet  fever,  erysipelas  or  any 
other  virulent  infectious  disease,  the  affected  person  shall  not 
come  upon  the  premises  of  the  company  or  resume  his  work 
until  he  shall  present  a  certificate  from  a  physician  to  the 
effect  that  he  is  no  longer  capable  of  conveying  infection.  The 
same  applies  to  employees  in  whose  dwelling  any  one  of  the 
above  named  diseases  may  occur. 

If  any  one  of  the  employees  shall  be  afflicted  with  discharg- 
ing or  suppurating  wounds  on  the  face,  hands  or  arms  or 
with  any  transmissible  or  repulsive  disease  or  with  severe 
diarrhoea,  the  affected  person  shall  not  be  employed,  during 
the  continuance  of  the  condition,  in  any  work  in  which  he 
would  come  into  direct  or  indirect  contact  with  milk,  nor 
shall  he  be  permitted  to  wash  bottles. 

Every  employee  who  may  not  work  on  account  of  illness, 
or  on  account  of  disease  in  his  family,  is  to  receive  his  full 
pay  as  though  working.  A  physician  is  appointed  with  whom 
the  employees  and  the  members  of  their  families  may  consult 
and  who  shall  make  frequent  visits  to  the  dairy  premises  and 
keep  an  oversight  of  the  employees  as  to  their  health. 

The  company  shall  keep  a  special  record  showing  the  em- 
ployees that  are  ill,  when  they  are  laid  off,  and  the  nature  of 
the  illness. 

6.  The  milk  shall  be  cooled  to  5°  C.   (41°  F.)   as  it  is  re- 
ceived from  the  producers  and  shall  be  kept  at  this  or  a  lower 
temperature. 

7.  All    containers 5S    are   to   be    thoroughly    cleaned   by    a 
method  approved  by  the  committee.     The  bottles  for  nursery 

58  The  milk  is  delivered  to  customers  only  in  sealed  cans  or,  in  the 
case  of  nursery  milk,  in  bottles. 


COMPANY  REGULATIONS  241 

milk  are  to  be   cleaned  and  heated  in   accordance  with  the 
instructions  of  the  committee. 

8.  The  herds  and  all  of  the  premises  connected  with  the 
business  are  to  be  open  to  the  members  of  the  committee  at 
all  times.     All  necessary  travelling  expenses  are  to  be  paid. 

9.  All  announcements  and  communications  regarding  the 
business,  so  far  as  these  relate  to  the  technical  matters  under 
the  supervision  of  the  committee,  are  to  be  approved  by  the 
committee  before  they  are  published. 

10.  A  member  of  the  committee  of  control  shall  be  privi- 
leged to  resign  (a)  at  any  time  when  in  his  opinion  the  hygienic 
regulations  relating  to  the   conduct  of  the  business  are  not 
properly  observed  and,  similarly,  if  later  regulations  made  by 
order  of  the  committee  are  not  complied  with,  or  (b)    [under 
other  circumstances]  he  may  resign  after  three  months'  notice. 

III.  REGULATIONS  CONCERNING  THE  PRODUCTION 
AND  CARE  OF  MILK 

A.     THE   HEALTH   OF  THE   HERDS 

1.  The   producer  must   agree   to   permit   the   veterinarian 
of  the  company  to  examine  his  herd  as  often  as  may  be  con- 
sidered by  the   company   to   be   necessary  and  he   must  give 
the  veterinarian  such  information  as  he  may  desire  in  regard 
to  the  herd,  the  feeding  and  the  milk. 

The  producer  must  agree  to  observe  the  instructions  of  the 
veterinarian. 

2.  The  cattle  that  are  designated  by  the  veterinarian   as 
tuberculous  are  to  be  removed  from  the  herd  at  once,  and,  as 
soon  as  possible,  they  are  to  be  sold  or  killed.     Cattle  that  for 
any  other  cause  are  picked  out  by  the  veterinarian  are,  as  he 
directs,  to  be  removed  from  the  stable  or  placed  apart  at  one 
end;  the  milk  may  not  be  used   and  the   cows  may  not  be 
restored  to  their  places  with  the  herd  until  permission  is  given. 

3.  In  case  disease  occurs  between  the  visits  of  the  veter- 
inarian, and  especially  any  of  the  following, — tuberculosis,  in- 
flammation of  the  udder,  inflammation  of  the  uterus,  severe 
diarrhoea, — the  affected  animal  or  animals  are  to  be  isolated 

16 


242  MILK  HYGIENE 

and  their  milk  must  not  be  used.  The  company  will  con- 
tinue to  pay  for  this  milk  until  the  veterinarian  makes  an  in- 
spection. If  a  number  of  cows  become  diseased  in  such  a 
way  as  to  suggest  the  outbreak  of  an  epizootic  or  poisoning 
the  veterinarian  and  the  business  manager  of  the  company 
are  to  be  notified  at  once  by  telegraph  or  telephone. 

4.  The  milk  of  newly  purchased  cows  may  not  be  used  until 
these  cows  have  been  examined  by  the  veterinarian  and  ap- 
proved. 

5.  The  producers  of  nursery  milk  are  obligated  to  add  no 
cows  to  their  herds  until  they  have  been  tested  with  tuberculin 
and  are  declared  by  the  veterinarian  for  the  company  to  be 
healthy. 

All  of  the  cows  of  the  herd  are  to  be  tagged  by  the  veter- 
inarian. 

The  producer  is  required  to  have  his  herd  tested  with 
tuberculin  at  least  once  a  year.  The  records  of  test  are  to  be 
submitted  by  the  veterinarian  of  the  company  to  the  com- 
mittee. 

If  there  is  maintained  on  a  farm  a  herd  of  reacting  cows, 
the  producer  is  required  to  dispose  of  these  gradually  and  to 
take  care  that  there  is  no  contact  between  the  healthy  and  the 
reacting  cattle. 

B.  THE  HEALTH  OF  THE  PERSONNEL 

1.  The  producer  is  required  to  observe  the  following  rules 
in  relation  to  the  health  of  the  persons  who  work  in  the  stable 
or  with  the  milk: 

a.  No  one  may  be  employed  who  is  affected  with  tubercu- 
losis or  syphilis. 

6.  Persons  who  have  discharging  or  suppurating  sores  or 
wounds  on  the  face,  hands  or  arms,  or  a  disease  of  the  skin  of 
these  regions,  or  that  have  severe  diarrhoea  are  not  under  any 
circumstances  to  be  permitted  to  come  in  contact  with  the  milk. 

c.  Persons  who  live  in  a  house  where  there  is  typhoid 
fever,  gastric  fever,  diphtheria,  scarlet  fever  or  any  other 
virulent  infectious  diseases  are,  likewise,  positively  prohibited 
from  coming  in  contact  with  the  milk  until  the  local  physician 


COMPANY  REGULATIONS  243 

certifies  that  they  are  no  longer  infectious.  If,  nevertheless, 
such  persons  should  by  accident  come  in  contact  with  the  milk, 
it  is  to  be  held  back  (not  shipped)  and  the  company  will  pay 
the  usual  price  for  it,  unless  the  contamination  was  the  result 
of  connivance  on  the  part  of  the  producers. 

d.  The   producer   is   required  to   use   all   possible   care   in 
keeping  informed  as  to  the  condition  of  health  of  his  employees 
so  that  every  case  of  infectious  disease  may  be  discovered  and 
isolated  as  soon  as  possible. 

e.  Once  a  year — soon  after  the  "moving  days" — a  state- 
ment is  to  be  submitted  from  the  local  physician  to  show  the 
state  of  health  of  the  persons  on  the  farm  and  all  cases  of  in- 
fectious diseases  that  he  treated  [on  the  farm]  during  the  pre- 
ceding half  year. 

2.  If  a  case  of  typhoid  fever,  gastric  fever,  diphtheria, 
scarlet  fever  or  any  other  virulent  infectious  disease  occurs 
among  the  people  living  at  the  farmstead  or  among  the  people 
employed  on  the  farm,  the  producer  is  obligated  immediately 
to  notify  the  manager  of  the  company  by  telegraph  or  tele- 
phone. The  milk  shall  be  held  back  and  shipments  may  not 
be  resumed  until  the  committee  of  control  has  given  permis- 
sion. 

For  all  milk  that  is  held  back  under  these  circumstances 
the  company  will  pay  full  price. 

C.    FEEDING  AND  CARE  OF  THE  COWS 

1.  All  food  must  be  quite  fresh  [frisch — not  deteriorated]. 
Mouldy  or  otherwise  damaged  food  must  not  be  in  the  stable, 
or  in  the  immediate  vicinity.     The  veterinarian  of  the  com- 
pany has  the  right  to  inspect  the  food. 

2.  In  summer,  so  far  as  possible,  the  cows  are  to  be  fed 
in  the  pasture.     If  it  is  necessary  to  feed  them  in  the  stable, 
the  company  is  to  be  notified  and  then  the  producer  is  re- 
quired to  use  care  that  the  stable  and  the  cows  are  kept  as 
clean  as  possible. 

The  company  reserves  the  right  to  forbid,  if  it  is  considered 
necessary,  the  stable  feeding  of  cows  that  produce  nursery 
milk. 


244  MILK  HYGIENE 

3.  The  veterinarian  shall  be  advised  as  to  the  composition 
of  the  feed.     The  following  rules  apply: 

a.  No  roots  may  be  fed  to  cows  producing  nursery  milk 
except  carrots  and  sugar  beets,  and  of  these  not  more  than  20 
kilos  f40  Ibs.]  per  day. 

5.  Cows  producing  regular  milk  may  receive  as  much  as 
30  kilos  [60  Ibs.]  per  day,  provided  this  amount  does  not 
cause  diarrhoea. 

c.  Beet    tops,    beet    trimmings,    cabbage,    distillers'    slops, 
malt,  etc.,  may  not  be  fed. 

d.  For  cows  producing  nursery  milk,  the  following  foods 
are  prohibited:  molasses,  cotton-seed  meal,  green  or  dry  buck- 
wheat and  mustard.     These  feeds  may  be  given  to  other  cows, 
but  only  in  small  quantities.     Molasses  must  not  be  used  if  it 
produces  any  undesirable  effect. 

e.  If  rape  seed  is  used,  it  must  not  contain  any  consider- 
able quantity  of  oil  of  mustard,  and  before  it  is  used  it  must 
be  shown  to  the  official  veterinarian. 

4.  The  producer  is  required,  so  far  as  possible,  to  forbid 
frequent  and  sudden  changes  of  food. 

5.  Before  the  cows  are  stabled  in  the  fall,  the  hair  is  to  be 
clipped  from  the  udder,  tail  and  thighs. 

6.  The  use  of  beast  milk  is  forbidden  until  ten  days  after 
calving.     The  milk  shall  not  be  used  from  cows  that  have  daily 
less  than  3  kilos  [3  quarts]. 

D.     THE  CARE  OF  THE   MILK 

1.  Milking  must  be  conducted  with  the  highest  degree  of 
cleanliness  and  care.  The  following  specific  rules  shall  apply : 

a.  Each  milker  must  always  wear  a  milking  suit  and  must 
be  supplied  with  a  towel.  Clean  water  must  be  supplied  in 
ample  amount,  so  that  the  hands  may  be  washed  as  often  as 
necessary. 

Z>.  The  stable  must  be  so  well  lighted,  and  especially  behind 
the  cows,  that  those  who  do  the  work  can  see  clearly  enough  to 
perform  their  work  in  an  orderly  and  clean  manner. 

c.  Immediately   after   milking,    the   milk   is   to   be   passed 


COMPANY  REGULATIONS  245 

through   a   fine   metal   strainer,   Avhich   must   be   cleaned   fre- 
quently. 

d.  The  milk  is  to  be  cooled  before  it  is  shipped,  at  all  sea- 
sons, and  just  after  milking,  by  the  use  of  a  cooler,  to  at  least 
8°  C.  (46.4°  F.). 

e.  Mucking  out  shall  not  take  place  until  after  the  morn- 
ing milking,   and  in  the  afternoon  it  must  be  completed  at 
least  one  hour  before  milking. 

f.  Fresh  cows   [those  giving  beast  milk],  cows  which  give 
less  than  3  kilos   [3  quarts]   a  day,  and  cows  that  have  been 
separated  from  the  herd  by  the  veterinarian  shall  have  places 
in  the  end  of  the  stable,  so  that  it  will  not  be  possible  for  the 
milkers  to  mix  their  milk  with  that  of  the  cows  producing  milk 
for  the  use  of  the  company. 

2.  A  sufficient  supply  of  ice  shall  be  available.     For  cool- 
ing, an  apparatus  is  to  be  used  that  is  set  up  in  a  light,  clean 
room,  that  is  used  for  no  other  purpose,  and  each  time,  before 
used,  it  is  to  be  rinsed  off  with  clean  water. 

3.  The  producer  agrees  to  follow  the  instructions  regard- 
ing cleanliness  in  the  stable  and  the  care  of  the  milk  that  may 
be  given  him  by  the  company  or  by  their  veterinarian. 

£.     DELIVERY 

1.  In  the  summer  the  transport  wagons  must  be  supplied 
with  a  cover  to  protect  the  milk  cans  from  the  sun. 

Feed,    fertilizer,   etc.,   must  not   be   carried   on   the   same 
wagon  with  milk  or  with  the  cleaned  milk  containers. 

2.  The  company  furnishes  the  cans  used  for  transporting 
the  milk.     Those  used  for  nursery  milk  must  not  be  used  for 
other  milk.     Under  no  circumstances  shall  the  cans  be  used 
for  any  purpose  other  than  to  send  milk  to  the  milk  station. 
The  cans  are  cleaned  by  the  company  before  they  are  returned. 

3.  The  producers  are  to  rinse  the  cans  in  clean,  cold  water, 
and,  if  soiled  during  transportation,  they  are  to  be  cleaned. 

4.  The  producer  is  required  to  furnish  a  supply  of  good 
water  for  the  cows  and  for  cleaning  the  vessels  and  utensils 
that  come  in  contact  with  the  milk.     Any  suspected  defect  of 


246  MILK  HYGIENE 

the  water  supply  is  to  be  reported  at  once  to  the  committee  on 
control. 

F.     OTHER   PROVISIONS 

1.  The  producer  agrees  to  answer  truthfully  and  honestly 
all  questions  from  the  company  in  regard  to  the  milk  supply. 

2.  It  is  agreed  that  the  herds  and  premises  where  the  milk 
is  handled  and  cared  for  shall  be  open  at  all  times  to  the  mem- 
bers of  the  committee  on  control. 

IV.    INSTRUCTIONS  TO  THE  VETERINARIANS 

The  veterinarians  are  appointed  and  can  only  be  dismissed 
by  the  committee  on  control,  and  all  instructions  come  from 
this  committee. 

A  report  is  to  be  rendered  to  the  committee  on  every  visit 
to  a  herd,  and  this  shall  contain  information  in  regard  to: 
the  total  number  of  cows,  the  cows  in  milk,  all  cases  of  disease, 
whether  cows  have  been  sold  or  killed  that  were  isolated  as 
suspicious  or  diseased,  the  condition  of  the  whole  establish- 
ment in  respect  to  cleanliness,  the  method  of  feeding  and  re- 
marks on  any  pertinent  subject. 


[It  is  especially  to  be  noted,  in  respect  to  the  above  regula- 
tions, that  they  are  planned  not  for  the  purpose  of  measuring, 
by  means  of  a  laboratory  examination,  the  extent  to  which  milk 
has  become  contaminated,  but  for  the  purpose  of  preventing 
contamination. 

The  most  injurious  bacteria  in  milk  are  the  pathogenic 
forms  that  come  from  diseased  persons  or  cattle  and  the  putre- 
factive organisms  that  come  from  diseased  cows,  dirty  prem- 
ises or  utensils  or  faulty  methods  of  milking  or  handling  milk. 
The  most  important  pathogenic  forms  cannot  be  detected  in 
milk  by  the  usual  routine  methods  in  use  in  milk  laboratories, 
if  at  all.  And  if  these  organisms  are  detected  by  laboratory 
examination  it  is  not  until  long  after  the  milk  has  been  con- 
sumed. Nor  can  the  injurious  saprophytes  be  identified  in 
the  laboratory  until  too  late  to  prevent  the  use  of  milk  con- 


COMPANY  EEGULATIONS  247 

taining  them.  Hence,  it  must  be  clear  that  the  truest  protec- 
tion to  the  consumer  consists  in  guarding  the  source  of  the 
milk  and  the  milk  itself,  from  conditions  that  are  known  to  be 
accompanied  by  danger  of  injurious  contamination. 

The  value  of  laboratory  examinations  as  to  the  number  and 
kind  of  bacteria,  pus  cells  and  solid  dirt  is  not  under-esti- 
mated; it  is  very  great  as  a  measure  of  the  thoroughness  of 
the  precautions  taken  on  the  dairy  farm,  and  during  shipping. 
But  the  value  of  this  examination  should  not  be  exaggerated, 
as  appears  to  be  the  tendency  in  some  quarters,  and  it  should 
not  be  thought  that  any  laboratory  examination  can,  with 
safety,  be  permitted  to  take  the  place  of  regular,  expert  veter- 
inary inspections  of  the  cattle,  methods  and  premises. 

The  bacteriologic  and  microscopic  examinations  of  milk  that 
are  made  in  public  health  laboratories  keep  contaminated  milk 
from,  entering  the  market  only  in  so  far  as  they  point  out  the 
necessity  for  the  veterinary  and  sanitary  control  of  dairy 
farms.  (See  quotation  from  Freeman  on  page  168.)  L.  P.] 


APPENDIX   II. 

The  following  instructions  in  regard  to  the  production  of 
nursery  milk  are  taken  from  a  circular  letter  of  May  27th, 
1899,  from  the  central  government  of  Germany  to  the  local 
governments. 

NURSERY  MILK 

"  The  special  establishments  for  producing  and  selling 
nursery  milk,  which  have  greatly  increased  in  number  in  re- 
cent times,  and  which  use  special  designations,  as  sanitary 
dairy,  health  milk,  children's  milk,  superior  milk,  etc.,  are  to 
be  looked  after  with  special  care  by  the  sanitary  authorities. 
The  general  methods,  the  cleanliness  of  the  stable,  the  store- 
room, the  utensils,  the  condition  of  health  of  the  cows  and  their 
feeding  and  care  are  to  be  placed  under  veterinary  oversight 

il  The  stables  shall  be  roomy,  light  and  airy,  and  they  shall 
have  impervious  floors  and  mangers  of  such  description  that 
they  can  be  easily  cleaned.  Running  water  shall  be  provided 
for  cleansing  and  the  drainage  shall  be  good.  Only  cows  for 
the  production  of  nursery  milk  shall  be  kept  in  such  special 
stables  and  these  cows  shall  be  marked  in  some  permanent 
way. 

' '  It  is  not  necessary  to  lay  down  special  regulations  for  feed- 
ing such  cows,  but  attention  should  be  called  to  the  known 
facts  as  to  injurious  effects  of  certain  cattle  foods  on  milk 
used  for  infant  feeding. 

"  In  general,  the  feeding  of  creamery  refuse  should  be  for- 
bidden on  account  of  the  danger  of  spreading  tuberculosis. 

"  The  condition  of  health  of  cows  designed  for  producing 
nursery  milk  is  to  be  determined  before  they  are  placed  in  the 
empire.  This  examination  is  to  be  repeated  at  intervals  of 
three  months. 

' '  A  careful  book  record  is  to  be  kept  of  these  examinations. 
The  official  who  is  charged  with  this  oversight  shall  make  an 
appropriate  entry  for  each  visit. 

249 


250  MILK  HYGIENE 

' '  The  occurrence  of  any  one  of  the  following  named  diseases 
among  the  cows  is  to  be  reported  at  once  to  the  official  veter- 
inarian: anthrax,  contagious  pleuro-pneumonia,  foot-and- 
mouth  disease,  black  quarter,  rabies,  cowpox,  icterus,  dysentery, 
inflammations  of  the  udder,  blood  poisonings,  especially 
pyaemia  and  septicaemia,  putrid  inflammation  of  the  uterus  or 
other  febrile  conditions,  retention  of  the  after-birth  and  con- 
ditions that  result  in  the  occurrence  of  discolored  milk. 

"  Cows  which  show  evidence  of  disturbance  of  digestion,  of 
diarrhoea  or  pica,  or  cows  that  are  suspected  of  being  afflicted 
with  tuberculosis  shall  at  once  be  removed  from  the  stable, 
until  the  animal  is  examined  and  the  condition  determined  by 
the  official  veterinarian. 

"  It  is  not  permitted  to  use  as  bedding  soiled  or  refuse 
straw  or  other  waste  material. 

' '  Cows  for  producing  nursery  milk  shall  be  kept  particularly 
clean.  Before  milking,  the  udder  is  to  be  carefully  cleaned. 
The  milkers  must  keep  themselves  thoroughly  clean.  They 
must  wash  their  hands  and  arms  with  soap  before  milking,  and 
wear  a  clean  frock.  Any  person  suffering  with  a  contagious 
or  eruptive  disease  must  not  be  permitted  to  milk." 


APPENDIX   III. 

Certified  milk  in  Philadelphia  is  produced  under  the  con- 
trol of  a  commission  organized  in  1899  under  the  following 
plan: 

1.  There  shall  be  a  Milk  Commission  of  the  Philadelphia 
Pediatric  Society,  whose  duty  it  shall  be  to  have  examined 
milk  submitted  to  them  by  dairymen  and  certify  as  to  the 
result  of  such  examination. 

2.  The  actions  of  the  Commission  shall  be  reported  from 
time  to  time  to  the  Society  and  shall  be  subject  to  its  approval. 

3.  The  Commission  shall  consist  of  four  members  besides  the 
President  of  the  Society,  who  shall  be  a  member  ex  officio.     The 
members  shall  be  appointed  yearly  by  the  President  as  soon 
as  possible  after  his  election.     The  Commission  shall  elect  a 
chairman  and  a  secretary  from  their  number. 

4.  No   statement   for  publication   or  information   to    any 
dairyman  shall  be  given  by  or  in  the  name  of  any  individual 
member,  but  only  after  consideration  by  the  Commission  and 
in  the  name  of  "The  Milk  Commission  of  the  Philadelphia 
Pediatric  Society." 

5.  The  Commission  will  hold  itself  in  readiness  to  examine 
milk  from  dairies  desiring  this  examination,  and  to  certify  to 
the  good  quality  of  milk  which  comes  up  to  the  standards  fixed 
by  it.     It  is  understood  that  only  the  milk  of  dairies,  and  not 
that  of  milkmen  who  merely  serve  milk  bought  by  them,  will 
be  examined  by  the  Commission. 

6.  The  method  of  examination  and  certification  to  which 
the  dairyman  or  his  agent  shall  agree  to  submit  shall  be  as 
follows : 

7.  The  Commission  shall  select  a  bacteriologist,  a  chemist, 
and  a  veterinary  inspector.     The  bacteriologist  shall  procure 
a  specimen  of  milk  from  the  dairy,  or,  preferably,  from  de- 
livery wagons,  at  intervals  to  be  arranged  between  the  Com- 
mission and  the  dairy,  but  in  no  case  at  a  longer  interval  than 

251 


252  MILK  HYGIENE 

one  month.  The  exact  time  of  the  procuring  shall  be  with- 
out previous  notice  to  the  dairy.  He  shall  test  this  milk  for 
the  number  and  nature  of  bacteria  present  in  it,  to  the  extent 
which  the  needs  of  safe  milk  demand.  He  shall  also  make  a 
microscopic  examination  of  the  milk  for  pus  cells.  Milk  free 
from  pus  and  injurious  germs  and  having  not  more  than 
10,000  germs*  of  any  kind  or  kinds  to  the  cubic  centimeter, 
shall  be  considered  to  be  up  to  the  required  standard  of  purity. 

8.  The  chemist  shall  in  a  similar  manner  procure  and  ex- 
amine the  milk  for  the  percentages  of  proteids,   fat,   sugar, 
mineral  matter,   and  water  present.     He   shall   also   test   its 
chemical  reaction  and  specific  gravity,  and  shall  examine  it 
for  the  presence  of  foreign  coloring  or  other  matters  or  chem- 
icals added  as  preservatives.     Standard  milk  shall  range  from 
1.029  to  1.034  specific  gravity,  be  neutral  or  very  faintly  acid 
in  reaction,  contain  not  less  than  from  3.5  per  cent,  to  4.5  per 
cent,  proteid;  from  4  per  cent,  to  5  per  cent,  sugar,  and  not 
less  than  3.5  per  cent,  to  4.5  per  cent,  fat  in  the  case  of  4  per 
cent,  fat  milk,  and  shall  be  free  from  all  contaminating  foreign 
matter  and  from  all  addition  of  chemical  substances  or  color- 
ing matters.     Richness  of  cream  in  fat  shall  be  specified  and 
shall  vary  not  more  than  1  per  cent,  above  or  below  the  figure 
named  in  selling.     Neither  milk  nor  cream  shall  have  been 
subjected  to  heat  before  the  examination  has  been  made,  nor 
at  any  time,  unless  so  announced  to  the  consumer. 

9.  The   veterinary   inspector   shall,   at   intervals   equal   to 
those  of  the  bacteriologist  and  chemist,  and  without  previous 
warning  to  the  dairy,  inspect  the  cleanliness  of  the  dairy  in 
general,  the  care  and  cleanliness  observed  in  milking,  the  care 
of  the  various  utensils  employed,  the  nature  and  quality  of  the 
food  used,  and  all  other  matters  of  a  hygienic  nature  bearing 
upon  the  health  of  the  cows  and  the  cleanliness  of  the  milk, 
including  also  as  far  as  possible  the  inquiry  into  the  health  of 
the  employees  on  their  farms.     He  shall  also  see  that  the  cows 
are  free  from  tuberculosis  or  other  disease. 

10.  The   charges  made  by  the  experts  shall  be — for  the 
veterinarian  $10.00,  and  $5.00  for  each  of  the  others  for  each 
examination;  this  amount  to  be  paid  by  the  dairy  at  the  time 


PLAN  FOR  COMMISSION  253 

of  the  examination  and  without  regard  to  whether  the  report 
is  favorable  or  unfavorable.  The  experts  shall  make  their 
examinations  when,  and  only  when,  notified  to  do  so  by  the 
Commission.  Any  dairy  the  milk  of  which  shall  be  found  by 
the  examiners  to  be  up  to  the  standard  of  the  Commission 
shall  receive  a  certificate  from  the  Commission,  which  shall 
read  as  follows: 

MILK.  COMMISSION  OF  THE   PHILADELPHIA 
PEDIATRIC  SOCIETY 

Date 

The  Veterinary  Inspector  of  the  Commission  has  examined 

the  dairy  of  Mr and  reports  it  to  be  well  kept  and 

clean,  and  the  cows  to  be  in  a  healthy  condition. 

The  Bacteriologist  reports  that  the  milk  does  not  contain 
germs  beyond  the  limits  of  the  standards  of  the  Commission. 

The  Chemist  reports  that  the  milk  is  of  standard  richness, 
and  that  he  has  discovered  in  it  no  impurities,  coloring  mat- 
ters, chemical  preservatives,  or  harmful  substances. 

The  Commission  certifies  to  these  statements  of  the 
examiners.  It  is  understood  and  agreed  to  by  the"  said 

Mr that   this   certificate   is   good   for   not   more 

than from  date,  when  another  examination  is  to  be 

made. 

[Signed  by  the  Commission.] 

11.  In  case  an  examination  shows  the  milk  not  to  be  up  to 
the  standard  the  dairy  may  have  a  re-examination  made  within 
a  week  or  within  a  short  time,  at  the  discretion  of  the  Commis- 
sion. 

12.  Milk   furnished   by   the   dealers    to   whom    certificates 
have   been   issued   shall   be   furnished   to   consumers   in   glass 
bottles  hermetically  sealed  in  a  manner  satisfactory  to  the  Com- 
mission.    In  addition  to  the  sealing,  and  as  a  guarantee  to  the 
consumer  that  the  examination  has  been  regularly  conducted, 
there  shall  be  pasted  over  the  mouth  of  the  jar,  or  handed  to 
the  consumer  with  every  jar,  according  to  the  discretion  of 
the  Commission,  a  certificate  slip  which  shall  read  as  follows : 


254  MILK  HYGIENE 


PHILADELPHIA  PEDIATRIC  SOCIETY. 

MILK    COMMISSION   CERTIFICATE. 


Milk  from  the  dairy  of  Mr has  been  recently 

examined  by  the  experts  of  the  Milk  Commission  and  found  to  be  up  to  the  required 
standards.  Another  examination  is  to  be  made  within  a  month,  and,  if  satisfactory, 
new  labels  for  the  bottles  will  be  issued,  dated 


NOTICE    THE    DATES. 


The  blanks  used  by  the  experts  of  the  Commission  in  re- 
porting to  the  secretary  are  as  follows: 


REPORT  OF  VETERINARIAN. 

Philadelphia, 190. .. 

Secretary  of  the  Commission, 

DEAR   SIR: — I  have  examined,   as  requested   by   the    Commission, 

the    dairy    of at 

and  find  the  following  conditions : — 

I milking  cows. 

hospital  cows. 

cows  sick  since  last  report. 

dry  cows. 

cows  recently  calved. 

cows  added  since  last  report. 

Did  they  pass  veterinary  inspection  and  the  tuberculin  test  before 

admission  to  the  milking  herd  ? 

cows  now  in  quarantine. 

Total  number  of  cows  in  herd of  which 

have  been  tested  with  tuberculin  in  the  past  year. 

II.     Food  employed. 


III.  Source  and  character  of  water  in  dairy  and  stables. 

IV.  Condition  of  Stables: 

Ventilation Heat 

Cleanliness,  etc 

Floors Troughs 

Condition  of  other  buildings 

V.     Health  of  employees  and  their  families,  as  far  as  ascertained, 
is 

VI.     The  general  precautions  of  cleanliness  in  milking  and  the  care 
of  the  milk  are 

I  therefore  recommend  that  milk  from  this  dairy  be  submitted  to  the 
Bacteriologist  and  Chemist  of  the  Commission  for  their  examinations. 
Yours  truly, Veterinarian. 


ESTIMATION  OF  QUALITY  255 

REPORT  OF   BACTERIOLOGIST. 

Philadelphia, 190.  .. 

Secretary  of  the  Commission, 
DEAR  SIR: 

At  the  request  of  the  Commission,  received  on 

milk 

,  190 .  . ,  cream  from  the  dairy  of 

labeled was  obtained  by  me  on 

190 ..,     at      Street,     at      o'clock. 

.  . .  .M.,  and  examined  at o'clock,  .  .  .  .M.,  with  the  following  results— 

milk 

Number  of  bacteria  per  c.c.  of  cream 

I    have  been  unable  to  detect  any  pathogenic  organisms  or  evidence 
of  purulent  inflammation  of  the  udder. 

milk 

I  therefore  recommend  the  cream  as  coming  up  to  the  bacteriologic 
standards  adopted  by  the  Commission. 

I   find  the  bottles  to    be  sealed   in  the  manner   prescribed   by  the 
Commission. 

Yours  truly, 
Bacteriologist. 

REPORT  OF  CHEMIST. 

Philadelphia, 190. .. 

Secretary  of  the  Commission, 
DEAR  SIR: 

At  the  request  of  the  Commission,  received  on 

milk 

190 .  . ,  cream  from  the  dairy  of 

labeled was  obtained  by  me  on 

190.  .,  and  examined  with  the  following  results: 

Fat,  (Leffman-Beam  method,)  

Total  proteids,  (Kjeldahl-Gunning  method,    factor   6.25),          

Preservatives,  added  color  and  heat,  none. 

Acidity,  

Specific  gravity,  

milk 

I  therefore  recommend  the  cream  as  coming  up  to  the  chemical 
standards  adopted  by  the  Commission. 

I  find  the  bottles  to  be  sealed  in  the  manner  prescribed  by  the  Com- 
mission. 

Yours  truly, 

.  .  Chemist. 


APPENDIX    IV. 

The  following  plan  for  estimating  the  quality  of  dairy 
farm  conditions,  and  for  making  it  possible  to  compare  farms, 
was  originated  and  arranged  by  R.  A.  Pearson,  Professor  of 
Dairy  Industry  at  Cornell  University. 

The  score  card  idea  has  been  extensively  employed  in 
judging  animals,  plants,  seeds,  etc..  but  this  is  the  first  adapta- 
tion of  this  principle  to  the  judging  of  such  a  complex  object 
as  a  dairy  farm,  including  all  of  the  factors  that  enter  into 
the  production  of  sanitary  milk.  A  special  feature  of  this 
scheme  is  the  division  into  groups;  a  low  score  in  any  group 
renders  the  whole  inferior,  no  matter  how  excellent  the  other 
groups  may  be. 

The  general  idea  is  an  excellent  one;  it  enables  the  in- 
spector to  record  in  convenient  form  a  summary  of  the  result 
of  his  inspection  and,  by  this  means,  a  comparison  can  readily 
be  made  between  the  conditions  of  a  farm  at  different  times. 
Some  practice  is  required  to  obtain  the  best  results  from  the 
use  of  this  method. 


257 


258 


MILK  HYGIENE 


Department  of  Dairy  Industry,   College  of  Agriculture, 
Cornell  University, 

Score  Card  for  Production  of  Sanitary  Milk. 


Date K .. .  Dairy  of 

Perfect]     Score 

'  Health  and  comfort  of  the  cows  and  their  isola- 

-T.  Health  of  the  tion  when  sick  or  at  calving  time 45 

herd  and  its  pro-  !  Location,  lighting  and  ventilation  of  the  stable. .  35 

lection  Food  and  water 20 

Total 100 

Cows 30 

II.  Cleanliness  of       Stable 20 

the  COWS  and  their   Barnyard  and  pasture 20 

surroundings            Stable  air  (freedom  from  dust  and  odors) 30 

Total 100 

Construction  of  utensils  and  their  cleaning  and 

III.  Construction  sterilizing 40 

and    care   of    the   Water  supply  for  cleaning  and  location  and  pro- 
utensils  Care  of  utensi]s  after  cleaning 20 

Use  of  small-top  milking  pail 15 

Total 100 

Health  of  employees 45 

IV.  Health     of    em-    Clean  over-all  milking  suits  and  milking  with 

ployees  and  clean,  dry  hands 30 

manner   nf    mill     Quiet  milking,  attention  to  cleanliness  of  the 

udder  and  discarding  fore  milk 25 

ing 

Total 100 

Prompt  and  efficient  cooling 35 

V.  Handling  the  Handling  milk  in  a  sanitary  room  and  holding  it 

at  a  low  temperature 35 

Protection  during  transportation  to  market 30 

Total 100 

TOTAL  OF  ALL  SCORES 500 

If  the  total  of  all  scores  is  And  each  division  is  The  sanitary  conditions  are 

480  or  above 90  or  above EXCELLENT 

450  or  above 80  or  above GOOD 

400  or  above 60  or  above MEDIUM 

Below  400 Or  any  division  is  below  60 POOR 

The  sanitary 

conditions  are Scored  by 


APPENDIX  V. 

On  account  of  its  historic  value,  the  following  agreement, 
which  was  the  first  provision  for  the  production  of  "certified 
milk"  in  America,  is  reproduced.  The  plan  of  the  agreement 
originated  with  Dr.  Henry  L.  Coit,  of  Newark,  N.  J.,  and  the 
1 '  party  of  the  first  party, ' '  of  the  contract  is  the  Medical  Milk 
Commission  of  Essex  County,  New  Jersey.  The  date  of  this 
agreement  was  May  9th,  1893.  It  is  still  in  force. 

1.  The  party  of  the  second  part  doth  hereby  agree  to  con- 
duct such  parts  of  his  dairy  as  may  be  hereafter  named,  collect 
and  handle  its  products  in  conformity  with  the  following  code 
of   requirements,   for   and   in   consideration   of   the   promised 
endorsement  of  the  parties  of  the  first  part,   as  hereinafter 
indicated.     The  milk  thus  produced  shall  be  known  as  certified 
milk;  shall  be  designed  especially  for  clinical  purposes,  and 
when  at  any  time  the  demand  shall  be  greater  than  the  supply, 
and  it  is  required  by  a  physician,  either  for  infant  feeding  or 
the  diet  of  the  sick,  it  is  hereby  agreed  that  such  shall  be  the 
preferred  purchaser. 

2.  The  party  of  the  second  part  further  agrees  to  pay  for 
chemical    and    bacteriological   examinations    of    the    aforesaid 
certified  milk,  at  such  time  as  in  the  judgment  of  the  party  of 
the  first  part  is  desirable. 

3.  He  also  agrees  to  defray  the  cost  of  a  bi-monthly  in- 
spection  of  his   dairy   stock,   or   oftener,   if   necessary,   by   a 
competent   and  approved  veterinarian,   all  of  which  persons, 
namely :  the  chemist,  the  bacteriologist,  the  veterinary  surgeon, 
shall  be  chosen  by  the  parties  of  the  first  part,  to  whom  they 
shall  render  their  reports  in  writing. 

4.  It  is  expressly  understood  and  agreed,  that  the  party 
of  the  second  part  shall  not  pay  more  than  the  sum  of  five 
hundred  dollars  in  any  one  year,  for  the  services  of  chemist, 
bacteriologist  and  veterinary  surgeon,  and  the  party  of  the 

259 


260  MILK  HYGIENE 

first  part  shall  limit  the  expense  of  such  service  to  that  amount. 
It  is  furthermore  agreed  that  the  party  of  the  second  part,  on 
receipt  of  a  certified  copy  of  the  reports  of  the  experts,  shall 
mail  to  the  persons  indicated  by  the  parties  of  the  first  part, 
and  not  to  others,  a  duplicate  printed  copy  of  the  aforesaid 
reports,  bearing  the  signatures  of  the  experts  and  the  names 
of  the  physicians.  The  same  to  be  issued  at  such  intervals  as 
in  the  judgment  of  the  parties  of  the  first  part  is  desirable; 
also  that  the  necessary  expenditures  for  printing  and  circula- 
tion be  met  in  the  same  way  as  herein  provided  for  expert 
examinations. 

LOCATION  OF  LANDS 

5.  It  is  hereby  understood  and  agreed,  that  the  lands  used 
by  the  owners,  agents  or  assigns  of  the  dairy,  conducted  by 
the  party  of  the  second  part,  and  employed  for  pasturage,  or 
any  lands  that  may  hereafter  be  acquired  for  such  purpose,  or 
such  lands  as  may  be  used  for  the  cultivation  of  hay  or  fodder, 
shall  be  subject  to  the  approval  of  the  parties  of  the  first  part. 

BUILDINGS 

6.  It  is  also  understood  and  agreed,  that  the  buildings,  such 
as  stables,  creamery,  dairy  house  and  spring  house,  shall  be 
constructed  after  the  most  approved  style  of  architecture,  in 
so  far  as  construction  may  affect  the  health  of  the  dairy  stock, 
or  the  character  and  conditions  of  the  milk. 

7.  The  buildings,  used  for  the  housing  of  the  animals,  shall 
be  situated  on  elevated  ground,  and  capable  of  being  properly 
drained. 

8.  Said  buildings  to  be  sheltered  from  cold  winds,  lighted 
and  ventilated  according  to  approved  hygienic  methods.     The 
buildings  shall  be  constructed  so  as  to  favor  the  prompt  and 
easy  removal  of  waste  products. 

9.  The  apartments  used  for  the  storage  of  either  feed  or 
fodder  shall  be  removed  from  possible  contamination  by  stable 
waste  or  animal  odors. 

10.  All  buildings  shall,  in  addition  to  healthy  location,  ap- 
proved construction  and  proper  ventilation,  be  kept  free  from 
animal  or  vegetable  matter  in  a  state  or  process  of  decomposi- 


FIRST  AMERICAN  AGREEMENT          261 

tion  or  decay,  and  always  free  from  accumulations  of  dust  or 
mould. 

THE  WATER  SUPPLY 

11.  The  dairy  shall  be  supplied  with  an  abundance  of  pure 
water. 

12.  No  water  from  shallow  wells  or  springs  holding  sur- 
face drainage,  shall  be  used  for  watering  stock,  cooling  milk 
or  cleaning  vessels. 

13.  Nor  shall  any  well  or  spring  be  located  within  three 
hundred  feet  of  the  stable. 

SURROUNDINGS 

14.  It  is  further  understood  and  agreed  that  the  immedi- 
ate surroundings  of  the  buildings  shall  be  kept  in  a  condition 
of  cleanliness  and  order.     There  shall  not  be  allowed  to  ac- 
cumulate in  the  vicinity  any  loose  dirt,  rubbish  or  decayed 
vegetable  or  animal  matter,  or  animal  waste. 

15.  Nor  shall  there  be  within  three  hundred  yards  of  any 
building,  any  constantly  wet  or  marshy  ground,  or  stagnant 
pools  of  water. 

16.  Nor  shall  there  be   kept  within  three  hundred  yards 
of   any   building   used   for   dairy   purposes   any    fowls,   hogs, 
horses  or  other  live  stock. 

THE  cows 

17.  It  is  hereby  understood  and  agreed  that  the  following 
unhealthy  conditions  shall  be  a  sufficient  reason  to  exclude  any 
animal  from  the  herd  used  for  any  purpose  in  the  aforesaid 
dairy:  Any  animal  that  is  judged  by  a  competent  observer  to 
suffer  from  tuberculosis,  even  though  the  disease  be  localized 
in  a  part  distant  from  the  vital  organs. 

18.  Any  animal  with  fever.     Any  animal  suffering  from 
septic  absorption  or  other  disease,  following  or  associated  with 
parturition. 

19.  Any    animal    suffering    from   mammitis    or   mammary 
abscess. 

20.  Any  animal  with  persistent  diarrhoea  or  any  other  ab- 
normal physical  condition,  which  could  in  any  way  be  detri- 
mental to  the  character  of  the  milk. 


262  MILK  HYGIENE 

21.  It  is  furthermore  agreed  that  when  an  animal  shall  be 
found  by  a  competent  observer  to  be  in  a  state  of  ill  health, 
prejudicial  either  to  the  other  animals  in  the  herd  or  to  human 

health,  the  same  shall  be  removed  immediately,  and  if  neces- 
sary, shall  be  killed. 

22.  It   is   also   understood   and   agreed   that   the   party   of 
the  second  part  shall  exclude  from  the  herd  used  for  produc- 
ing certified  milk,   immediately   after   discovery,   any   animal 
subject   to   the   following   conditions:    Any    animal   that   was 
bred  through  consanguinity  within  a  period  of  three  gener- 
ations. 

23.  And  from  this  time  forth,  any  animal  of  those  bred  by 
the  party  of  the  second  part,  used  for  producing  certified  milk, 
that  was  not,  as  a  heifer,  kept  sterile  during  its  first  twenty- 
seven  months. 

24.  Any  phenomenal  milker,  except  that  glandular  disease 
or  tuberculosis  has  first  been   excluded  for  a  competent  ob- 
server. 

25.  It  is  furthermore  agreed  that  if  at  any  time  it  is  de- 
sired by  the  parties  of  the  first  part,  that  a  different  breed  of 
milch  cows  should  be  substituted  for  the  one  in  use,  in  order 
that  the  standards  of  quality  in  the  milk  may  be  raised,  the 
party  of  the  second  part  will  endeavor  to  carry  the  same  into 
effect. 

HOUSING  AND  CARE 

26.  It  is  furthermore  agreed,  that  the  dairy  stock  employed 
in  the  production  of  certified  milk,  shall  be  properly  sheltered 
from  the  influences  of  weather  and  climate  prejudicial  to  their 
health ;  also  that  the  animals  shall  be  kept  clean,  groomed  every 
day.  and  treated  kindly  at  all  times. 

27.  The  waste  products  of  the  stable  shall  be  removed  so 
frequently,  and  the  stable  floor  so  thoroughly  cleaned,  that  the 
same  shall  be  as  free  as  possible  from  animal  odors. 

28.  It  is  also  agreed  that  no  milch  cow  shall  be  used  for 
dairy  purposes  while  in  a  state  of  excitement,  either  as  a  result, 
or  during  the  period  of  estrux,  or  which  has  been  made  nervous 
either  by  heating,  whipping,  kicking,  prodding  or  running. 


FIRST  AMERICAN  AGREEMENT          263 

FEEDING 

29.  It  is  hereby  understood  and  agreed  that  the  methods 
of  feeding  the  cows  furnishing  the  certified  milk,  shall  be  sub- 
ject to  the  approval  of  the  parties  of  the  first  part.     The  feed 
and  fodder  shall  consist  only  of  nutritious  and  wholesome  ma- 
terials; such  as  grass,  clover  and  timothy  hay,  whole  grain,  or 
the  entire  result  of  the  grist.     No  materials  shall  be  employed 
which  are  or  may  become  injurious  to  the  health  of  the  ani- 
mals.    There  shall  not  be  fed  at  any  time,  or  in  any  quantity, 
either  alone  or  mixed  with  other  feed  or  fodder,  hulls,  screen- 
ings, wet  or  dry  brewers'  grains,  oil  cake,  sour  ensilage,  the 
refuse  from  distilleries,  glucose  or  starch  factories,  any  waste 
by-product  in  the  treatment  of  grain,  low  marsh  grass,  or  any 
of  the  questionable  or  exhausted  feeds  or  fodders  employed 
either  to  increase  the  milking  capacity  of  the  animal,  or  that 
will  produce  an  impoverished  milk,  or  that  will  impart  to  it 
unnatural  odors  or  flavors.     Nor  shall  the  cows  be  allowed  to 
eat  green  or  worm-eaten  fruit,   poisonous  weeds  or  to  drink 
poisonous  or  stagnant  water. 

COLLECTING  AND  HANDLING 

30.  It  is  furthermore  understood  and  agreed,  that  the  cows 
from  which  is  obtained  certified  milk  shall  be  milked  only  in  a 
clean  building,  and  not  an  illy-ventilated  stable  containing  foul 
odors  and  bad  air. 

31.  No   animal   furnishing   certified   milk   shall   be   milked 
until  the  udder  shall  first  have  been  cleaned  in  a  manner  ap- 
proved by  the  parties  of  the  first  part. 

32.  No  person  shall  be  allowed  to  draw  the  milk  that  has 
not  within  fifteen  minutes  of  the  milking  first  washed  his  or 
her  hands,  using  soap  and  nail  brush,   and  afterward  thor- 
oughly rinsing  the  hands  in  clean  water. 

33.  The  person  or  persons  engaged  in  milking  shall  also  be 
dressed  in  clean  over-clothes. 

34.  No  person  shall  be  allowed  to  draw  the  milk  who  has 
been  engaged  with  the  care  of  horses  in  the  same  clothing  or 
without  first  washing  his  hands. 

35.  No  milk  shall  be  represented  as  certified  milk  that  is  not 


264     ;£  MILK  HYGIENE 

received  from  the  udder  into  vessels,  and  from  these  into  cool- 
ing cans,  both  of  which  are  perfectly  clean  and  dry,  having  been 
cleansed  and  heated,  at  a  temperature  adequate  to  effect  com- 
plete sterilization,  since  the  last  milking;  and  have  been  kept 
inverted  in  a  clean,  dry  and  odorless  atmosphere. 

36.  No  milk  shall  be  represented  as  certified  milk  that  has 
not  been  passed  through  a  sieve  of  wire  or  other  cloth,  either 
while  milking  or  immediately  thereafter,  having  not  less  than 
one  hundred  meshes  to  the  linear  inch. 

37.  No  milk  shall  be  represented  as  certified  milk  that  does 
not  consist  of  the  entire  contents  of  the  udder  at  each  milking, 
including  the  fore-milk,  middlings  and  strippings. 

38.  No  milk  shall  be  represented  as  certified  milk  that  has 
been  drawn  from  the  animal  at  abnormal  hours,  such  as  mid- 
night or  noon ;  nor  from  any  animal  for  a  period  of  nine  Aveeks 
before  calving,  or  that  has  not  been  separated  for  nine  days 
after  parturition. 

39.  No  milk  shall  be  represented  as  certified  milk,  which 
has  been  exposed  to  the  emanation  or  infection  of  any  form 
of  communicable  disease,  either  in  the  person  or  persons  hand- 
ling the  milk,  or  by  accidental  contamination  in  cleaning  milk 
containers,   or  by  the  association  of  any  person   engaged  in 
handling  the  milk,  with  person  or  persons  sick  of  contagious 
disease. 

PREPARATION  FOR  SHIPMENT 

40.  It  is  hereby  understood  and  agreed,  that  all  milk  repre- 
sented as  certified  milk  shall  receive  every  known  detail   of 
care  that  will  promote  its  keeping  qualities,  and  favor  its  safe 
transportation. 

41.  That  the  milk  on  being  drawn  from  the  cow,  shall  be 
treated  by  ice,  or  clean,  cold  water  in  motion  and  proper  aera- 
tion, in  order,  first,  to  remove  its  animal  heat,  and  second,  to 
reduce  its  temperature  to  a  point  not  above  fifty  degrees,  nor 
below  forty  degrees  Fahrenheit ;  said  temperature  to  be  ac- 
quired within  forty-five  minutes  after  milking,  and  maintained 
within  the  above  limits  while  held  for  shipment,  during  its 
transportation  and  until  it  is  delivered  to  the  purchaser. 


FIRST  AMERICAN  AGREEMENT          265 

42.  That  the  cooling  of  the  milk  shall  not  be  conducted  in 
the  same  building  in  which  it  is  drawn,  nor  in  an  atmosphere 
containing  dust  or  tainted  with  animal  odors. 

43.  That  all  the  foregoing  provisions  concerning  the  cleans- 
ing and  condition  of  vessels  or  utensils  shall  be  complied  with 
in  the  said  cooling  process. 

44.  It  is  furthermore  agreed,  that  no  milk  shall  be  repre- 
sented as  certified  milk,  that  has  been  changed  or  reduced  in 
any  way,  by  the  addition  of  water  or  any  solid  or  liquid  sub- 
stance, in  or  out  of  solution,  or  the  subtraction  or  removal, 
in  any  manner,  of  any  part  thereof. 

45.  It  is  hereby  understood  and  agreed,  that  all  milk  to  be 
represented   as  certified  milk,   shall  be  packed   in  flint   glass 
quart  jars  immediately  after  it  is  cooled. 

46.  Said  jars  to  be  of  a  pattern  approved  by  the  parties 
of  the  first  part. 

47.  It  is  furthermore  agreed  that  the  bottles  or  jars,  before 
being  used,  shall  be  cleaned  by  hand,  separately,  with  the  aid 
of  hot  water,  alkaline  soaps,  rotating  brush  and  steam,  and 
that  they  shall  be  rinsed  in  two  separate  baths  of  clean,  hot 
water  and  then  thoroughly  dried  and  kept  inverted  until  used, 
without  covers,  in  a  clean,  dry  atmosphere  free  from  odors. 

48.  It  is  agreed  that  the  jars  shall  be  filled  by  a  method 
approved  by  the  parties  of  the  first  part. 

49.  That  they  shall  be  sealed  after  all  air  has  been  excluded, 
by  the  most  approved  device  for  closing  them. 

50.  The  bottles  after  being  filled,  shall  be  labeled  across  the 
cap,  bearing  the  words  * '  Certified  Milk, ' '  with  the  name  of  the 
dairyman,  together  with  the  date  of  milking. 

51.  It  is  furthermore  agreed,  that  no  milk  shall  be  sold  as 
certified  milk,  that  is  more  than  three  hours  old  when  bottled, 
nor  more  than  twenty-four  hours  old  when  delivered. 

TRANSPORTATION  AND  DELIVERY. 

52.  It  is  hereby  understood  and  agreed,  that  the  transporta- 
tion and  distribution  of  all  milk  represented  as  certified  milk, 
shall  be  conducted  by  the  party  of  the  second  part,  either  in 
person  or  by  persons  employed  by  him. 


266  MILK  HYGIENE 

53.  That  in  transit,  the  milk  shall  not  be  exposed  to  any 
of  the  foregoing  prohibitory  conditions. 

54.  That  it  shall  not  be  subjected  to  agitation. 

55.  That  it  shall  not  be  exposed  to  the  heat  of  the  sun. 

56.  That  the  delivery  wagons  shall  be  so  constructed  that 
the  required  temperature  of  the  milk  may  be  maintained  dur- 
ing transit. 

57.  That  before  the  wagons  are  filled  for  shipment,  the  body, 
the  trays  and  compartments  shall  be  tiushed  with  boiling  water. 

58.  It  is  furthermore  agreed  that  the  distributing  agents 
shall,  during  the  transfer  of  the  milk  from  the  dairy  to  the 
purchaser,  be  subject  to  the  following  restrictions,  namely : 

59.  That  they  shall  use  no  tobacco  or  intoxicating  drinks. 

60.  That  they  shall  not  collect  the  empty  containers,  nor 
receive  money  or  milk  checks  from  houses  in  which  an  infec- 
tious or  contagious  disease  is  known  to  exist. 

61.  It  is  also  hereby  agreed  that  the  collection  of  empty 
bottles,  from  places  where  infectious  or  contagious  disease  is 
known  to  exist,  shall  be  made  by  other  persons  that  those  em- 
ployed to  deliver  the  milk. 

62.  That  these  collections  be  made  with  wagons  not  em- 
ployed in  the  distribution  of  the  milk. 

63.  That  before  these  empty  bottles  shall  be  returned  to  the 
dairy,  they  shall  be  carried  to  a  separate  building  and  first  be 
subjected   to   the   process   of   cleaning   bottles   indicated   in   a 
former  clause  of  this  contract. 

64.  It  is  hereby  understood  and  agreed,  that  if  any  further 
precautions  or  changes  in  method,  calculated  to  improve  the 
quality  of  milk,  or  guard  the  same  from  impurities  or  dangers, 
are  desired,  that  the  party  of  the  second  part  will  cheerfully  be 
governed  by   such   additional   rules   and   regulations   as   may 
be  laid  down  by  the  parties  of  the  first  part. 

65.  It  is  understood  and  agreed  by  the  party  of  the  second 
part,  the  same  binding  the  owners,  agents  or  assigns  of  the 
aforesaid  dairy,  that  the  product  known  as  certified  milk  shall 
be  under  the  following  restrictions  in  its  sale,  namely:  That 
until   the   amount   required   within   the   boundaries   of   Essex 


FIRST  AMERICAN  AGREEMENT          267 

county  shall  first  be  supplied,  it  shall  not  be  sold  beyond  these 
limits,  except  that  the  parties  of  the  first  part  shall  give  their 
consent. 

66.  It  is  furthermore  agreed  by  the  party  of  the  second 
part,  the  same  binding  the  owners,  agents  or  assigns  of  the 
aforesaid  dairy,  that  in  the  event  of  a  failure  to  comply  with 
any  or  all  of  the  requirements  of  the  foregoing  contract,  the 
party  of  the  first  part  shall  reserve  the  right  to  withdraw  from 
the   contract,   and  publish  the   fact   in  such  manner   as  they 
deem  best. 

67.  Finally,  it  is  understood  and  agreed  that  nothing  in 
this  contract  shall  prevent  the  obrogation  of  any  of  the  pro- 
visions of  the  same,  by  the  parties  of  the  first  part,  provided 
that  it  shall  be  done  for  the  purpose  of  substituting  other 
provisions,  designed  to  promote  the  objects  of  their  organiza- 
tion. 

68.  It  is  further  understood  and  agreed  by  and  between 
the  parties  hereto,  that  the  party  of  the  second  part  shall  be 
at  liberty  to   cancel  this   agreement  by   giving  two  months' 
notice  in  writing,  of  his  desire  to  do  so,  in  case  of  inability  for 
any  reason,  to  comply  with  the  terms  of  the  same. 


APPENDIX  VI. 

The  Second  Interim  Report  of  the  Royal  Commission  on 
Human  and  Animal  Tuberculosis  was  issued  in  January,  1907. 
It  presents  the  conclusions  of  the  commission  after  thorough 
and  extensive  investigations  covering  more  than  five  years. 

The  report  is  signed  by  Sir  Michael  Foster,  Prof.  G.  Sims 
Woodhead,  Prof.  Sidney  Martin,  Sir  John  McFadyean  and 
Prof.  Rubert  Boyce. 

The  following  is  an  extract: 

CONCLUSION 

11  We  may  briefly  sum  up  the  bearings  of  the  results  at 
which  we  have  already  arrived  as  follows : 

"  There  can  be  no  doubt  but  that  in  a  certain  number  of 
cases  the  tuberculosis  occurring  in  the  human  subject,  es- 
pecially in  children,  is  the  direct  result  of  the  introduction  into 
the  human  body  of  the  bacillus  of  bovine  tuberculosis;  and 
there  also  can  be  no  doubt  that  in  the  majority  at  least  of 
these  cases  the  bacillus  is  introduced  through  cows'  milk. 
Cows'  milk  containing  bovine  tubercle  bacilli  is  clearly  a  cause 
of  tuberculosis  and  of  fatal  tuberculosis  in  man* 

li  Of  the  sixty  cases  of  human  tuberculosis  investigated  by 
us,  fourteen  of  the  viruses  belonged  to  Group  I,  that  is  to  say 
contained  the  bovine  bacillus.  If,  instead  of  taking  all  these 
sixty  cases,  we  confine  ourselves  to  cases  of  tuberculosis  in 
which  the  bacilli  were  apparently  introduced  into  the  body  by 
way  of  the  alimentary  canal,  the  proportion  of  Group  I  becomes 
very  much  larger.  Of  the  total  sixty  cases  investigated  by  us, 
twenty-eight  possessed  clinical  histories  indicating  that  in  them 
the  bacillus  was  introduced  through  the  alimentary  canal.  Of 
these,  thirteen  belong  to  Group  I.  Of  the  nine  cases  in  which 
cervical  glands  were  studied  by  us  three,  and  of  the  nineteen 

*  Original  not  italicized. 

269 


270  MILK  HYGIENE 

cases  in  which  the  lesions  of  abdominal  tuberculosis  were 
studied  by  us,  ten  belong  to  Group  I. 

' '  These  facts  indicate  that  a  very  large  proportion  of  tuber- 
culosis contracted  by  ingestion  is  due  to  tubercle  bacilli  of 
bovine  source. 

"  A  very  considerable  amount  of  disease  and  loss  of  life, 
especially  among  the  young,  must  be  attributed  to  the  consump- 
tion of  cows'  milk  containing  tubercle  bacilli.  The  presence 
of  tubercle  bacilli  in  cows'  milk  can  be  detected,  though  with 
some  difficulty,  if  the  proper  means  be  adopted,  and  such  ought 
never  to  be  used  as  food.  There  is  far  less  difficulty  in  recog- 
nizing clinically  that  a  cow  is  distinctly  suffering  from  tuber- 
culosis, in  which  case  she  may  be  yielding  tuberculosis  milk. 
The  milk  coming  from  such  a  cow  ought  not  to  form  part 
of  human  food,  and  indeed  ought  not  to  be  used  as  food  at  all. 

st  Our  results  clearly  point  to  the  necessity  of  measures 
more  stringent  than  those  at  present  enforced  being  taken 
to  prevent  the  sale  or  the  consumption  of  such  milk." 


OF  THE 

UNIVERSITY 

OF 


INDEX 


Abdominal  tuberculosis,  78 
Abnormal  coloration,  56 
odors  and  tastes,  55 
Abortion,  41 

Absorption    of    odors,    68,    69 
Acid,  benzoic,  64 

boric,  62 

citric,  150 

lactic,  52 

reaction,  227 

salicylic,  63 
Acid-fast  bacteria,  81 
Acidobutyrometer,  Gerber's,  209 
Actinomycosis,  92 

and  tumors,  48 
Addition  of  lactose  or  cane  sugar, 

221 

Admixture  of  dirt,  126, 127 
Advantages  derived  from  pasteur- 
izing market  milk,  138 
Adulteration,  frequency  of,  197 

of  cream,  225 

partly  skimmed  and  skimmed 

milk,  225 

Adulterations,  effects  of,  224 
Age  of  the  cow,  29 
Albumin,    14 
Alcohol   test,   229 
Alkalies,  68 
Alkaline  reaction,  227 
Alkaloids,  49 
Alpine  cattle,  milk  of,  40 
Amphoteric  reaction,  227 
Anthrax,   90 
Antiseptics,  61-68 
Appearance  of  milk,  226 
Arnold's  guaiac  method,  192 
Arsenic,  60 
Asiatic  cholera,  117 
Ass's  milk,  24 

Attendants,  health  of,  178,  185 
Automatic  temperature-regulator, 
134 


Babcock's  method,  214 
Backhaus's  infants'   milk,   151 
Bacteria,  acid-fast,  81 

in  dung  of  cows,  127 
market  milk,  122 
milk,    120 

of  putrefaction,  61,  229 

pathogenic,  129 

Bacteriological   examinations,   231 
Beast  milk,  12 
Beet  taste,  40 
Benzoic  acid,  64 
Bitch's  milk,  25 
Blue  milk,  56 

Board  of  Health  lactometer,  203 
Boiled  taste,  59 
Boric  acid,  62 
Breed  peculiarities,  27 
Buffalo's  milk,  23 
Burnt  taste,  40 
Buttermilk,    191 

Calf  cholera,  101,  125 
Carbohydrates,  18 
Carbolic  odor,  69 
Casein,  14,  16 
Catarrh,  mucous,  46 

purulent,  46 
Cat's  milk,  25 
Cell  protoplasm,  14 
Cells,  degenerated,  13 
Certified  milk  in  America,  259 

Philadelphia,  251 
Changes  in  milk,  51-58 

at  high  temperatures,  58,  59 
the  secretion,  46-48 
Cholera,  Asiatic,  117 

calf,  101,  125 
Citric  acid,  150 
Cleanliness,  176 
Colostrum,  12,  29,  30 

bodies,  12 

Composition   of  milk,   21-26 
271 


272 


INDEX 


Constituents  of  milk,  15-21 

Contamination  with  bacteria,  120- 

126 
organisms,  104-120 

Control  of  milk  in  cities,  197 

Contusions  of  the  udder  and  teats, 
45 

Cooler,  135 

Copenhagen  Milk  Supply  Com- 
pany, 159 

Cow,  disease  of,  42 

Cowpox,  89 

Cow's  milk,  21 

Cream,  191 

adulteration  of,  225 

Curd  fermentation,  230 

Daily  variations,  34 
Dairy  farm  inspector,  167,  168 
Degenerated  cells,  13 
Determination   of   fat   content   of 

milk,  208 
Digestion,  147 
Dilution  of  whole  milk  with  water, 

219 
Diphtheria,  112 

bacilli,  114 
Dirt,  127 
Disease  of  the  cow,  42 

Effects  of  various  adulterations, 

224 

Embolism  and  thrombosis,  45 
Enteritis,  98 

Examinations,  bacteriological,  231 
for  dirt,  235 

pus,  234 
Excretion  of  foreign  matter, 

48-50 
of    poisonous    substances    with 

milk,  60,  61 
Exercise  and  work,  42 

Farm  conditions,  257 
Fats,  19 

Fatty  degeneration,  14 
Feeding  the  herd,  173 
Fermentation,  curd,  230 

test,  229 
Feser's  lactoscope,  198 


Fjord  pasteurizer,  132,  133 
Food,  influence  of,  37 
Foot-and-mouth  disease,  87 

virus  of,  89 

Foreign  matter,  excretion  of,  48 
Formaldehyde,  66 
Formalin,  66 
Forinol,  66 

Galactase,  20 

Gangrenous  mastitis,  47 

Gartner's  fat  milk,  151 

Gases,  20 

Gerber's  acidobutyrometer,  209 

Globulin,  14 

Goat's  milk,  23 

Half  milk,  190 

skimmed  milk,  190 
Harmful  properties  of  milk,  60 
Health  of  the  attendants,  178 
Herd,  attendants  of,  178 

feeding  the,  173 

health  of,  169 

sample,  201 

sudden  changes  in  food  of,  176 

Indigestion,  101 
Individual  peculiarities,  28 
Infant  mortality,  126 
Infection  by  milk,  70—104 
Infectious  diseases,  103 
Influence  of  food,  37 
Inorganic  salts,  20 
Inspection  of  the  milk,  10  ._ 
Intestinal  tuberculosis,  72 
Iodine,  60 

Lactalbumin,  18 

Lactation  period,  29 

Lactic  acid,  52 

Lactodensimeter,   Quevenne's,   202 

Lactoglobulin,  18 

Lactometer,  Board  of  Health,  203 

Lactoscope,  Feser's,  198 

Lactose,  14,  18,  221 

Lecithin,  150 

Leffmann-Beam   method,   213 

Legal  standards,  187,  188 

Lung  plague,  92 


INDEX 


273 


Mare's  milk,  23 
Mastitis,  46,  93,  125 

gangrenous,  47 

parenchymatous,  47 
Medicines,  43 
Mercury,  60 
Method,  Arnold's  guaiac,  192 

Babcock,  214 

Leffmann-Beam,  213 

Soxhlet's,  208 

Storch's,  192 
Metritis,  125 
Milk,  acidity  of,  228 

appearance  of,  226 

ass's,  24 

Backhaus's  infants',  151 

bacteria  in,  120 
market,  122 

beast,  12 

bitch's,  25 

blue,  56 

bottling  of,  196 

buffalo's,  23 

care  of,  180 

certified,  251 

changes  in,  51-59 

commission,  163 

composition  of,  21-26 

constituents,  15-21 

containers,  193 

control,  9,  10 
of  in  cities,  197 

cow's,  21 

determination  of  fat  content 
of,  208 

dilution  of  whole  with  water, 
219 

elephant's,  26 

epidemics,  104 

fat,  19 

for  infants,  147 

Gartner's  fat,  151 

glands,  12-15 

goat's,  23 

half,  190 

skimmed,  190 

harmful  properties  of,  60 

infection  by,  70-104 

inspection  of,  10 


Milk,  keeping  and  selling,  184 

legal  standards  for,  188 

mare's,  23 

modified,  152 

nursery,  249,  250 

odor  of,  226 

of  the  Alpine  cattle,  40 

of  the  cat,  25 

packing  of,  185 

pasteurized,  191 

pasteurizing  market,  138 

preparations,  193 

preparing  for  delivery,  182 

public  control  of,  157,  158 

public  supervision  of,  196,  226 

putrid,  123 

rabbit's,  26 

red,  56 

regulation  of  production  of, 
164-181 

regulation  of  sale  of,  182-196 

reindeer's,  26 

retailing  in  cities,  159 

sale  and  delivery  of,  182 

secretion,  12-15 

sheep's,  23 

sickness,  103 

skimmed,  190 

slimy,  124 

specific  gravity  of,  197,  202 

sterilization  of,  142 

sterilized,  192 

sour,  123 

sow's,  25 

taste  of,  226 

transparency  of,  197 

tubercle  bacilli  in,  73 
mixed,  81 

unclean  or  dirty,  235 

variations  in,  24—26 

Voltmer's  mother's,  151 

voluntary  control  of,  163 

whole,  186 

woman's,  24 

yellow,  57 

zebu's,  22 
Milking,  method  of,  31 

time  of,  31 
Miliary  tuberculosis,  73 


274 


INDEX 


Modified  milk,  152 

Mortality  among1  children,  154 

Mucous  catarrh,  46 

Nitrate  and  nitrites,  221 
Nursery  milk,  249,  250 
Nymphomania,  41 

Odor,  carbolic,  69 

of  milk,  227 
Odors,  69 

abnormal,  55 

absorption  of,  68,  69,  70 
(Estrum,  41 
Oily  taste,  56 
Ovariotomy,  41 

Paracasein,  17 
Parenchymatous  mastitis,  47 
Partial  skimming,  218 
Partly  skimmed,  adulteration  of, 

225 
Pasteurization,  128-142 

objections  to,  139 

quick,  131 

Pasteurized  milk,  191 
Pasteurizer,  Fjord,  131 
Pasteurizing  a  fluid,  128 

market  milk,  138 
Pathogenic  bacteria,  129 
Pepsin  digestion,  17 
Peptone,  123 
Potassium  bichromate,  65 
Preparing  for  delivery,  182 
Preservatives,  61—68 
Preserving  samples  for  analysis, 

201 

Proteids,  16 

Pseudo-tubercle    bacilli,    81 
Public  supervision,  196,  226 
Purulent  catarrh,  46 
Putrid  milk,  123 

Quevenne's  lactodensimeter,  202 

Rabbit's  milk,  26 
Rabies,  91 

Rapid  method  for  determining 
acidity  of  milk,  228 


Reaction,  227 

acid,  227 

alkaline,  227 

amphoteric,  227 
Red  milk,  56 
Regenerative  heater,  144 
Regulation  of  production,  164- 

181 

sale,  182-196 
Reindeer's  milk,  26 
Retailing  milk  in  cities,  159 

Sale  and  delivery,  182 
Salicylic  acid,  63 
Salts,  20 

Sample,  herd,  201 
Samples,   preserving,   201 

taking,  200 
Scarlet   fever,  115 
Sediment,  126 
Septic  metritis,  101 
Sexual  conditions,  significance  of, 

40 

Sheep's  milk,  23 
Skimmed  milk,  190 
Skimmed  milk,  adulteration  of, 

225 

Skimming  of  whole  milk  in  con- 
junction    with     addition     of 

water,  222 
partial,  218 
Slimy  milk,  124 
Soapy  taste,  56 
Sore  throat,  119 
Sour  milk,  123 
Sow's  milk,  25 
Soxhlet's  method,  208 
Specific  gravity,  197 

of  milk  and  whey,  202 

whey,  206 

Stage  of  the  lactation  period,  29 
Sterilization,  130,  142-146 
Sterilized  milk,  192 
Storch's  method,  192 
Sudden  changes  in  food  of  herd, 

176 
Suppurative  processes,  102 

Tabes  mesenterica,  78 
Taking  samples,  200 


INDEX 


275 


Taste,  beet,  40 
boiled,  59 
burnt,  40 
of  milk,  229 
oily,  57 
soapy,  57 

Tastes,  abnormal,  55 
Temporary  changes,  38 
Test,  alcohol,  229 

fermentation,  229 
Transparency  of  milk,  197 
Trifolium  Milk  Supply  Co., 

239-247 

Toxic  substances,  60 
Tubercle  bacilli  in  milk,  72 

mixed   milk,   81 
separation  of,  85 
temperature   at   which   killed, 

86 

Tuberculosis,  71-87 
abdominal,  78 
broncho-pneumonia,  72 
in  cattle,  71 
intestinal,  72 
miliary,  73 
udder,  48,  71 
Tumors,  48 
Typhoid  bacillus,  110 
'fever,  106 


Unclean  or  dirty  milk,  235 
Udder  and  teats,  contusion  of,  45 

inflammation  of  (mastitis),  93 

fledema,  46 

tuberculosis,  48,  71 
Unsanitary  practices  in  bottling, 
195,  196 

Variations  in  cow's  milk,  26-45 

Viscogen,  226 

Viscosity,  58 

Volatile  oils,  60 

Voltmer's  mother's  milk,  151 

Voluntary  control  of  milk,  163 

Water,  16 

supply,  179 
Whey  proteid,  17 

specific   gravity  of,   202,  206 
Whole  milk,  186 

dilution  of  with  water,  219 
skimming  of  in  conjunction 

with  water,  222 
Woman's  milk,  24 

Yellow  milk,  57 
Zebu's  milk,  22 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 

THIS  BOOK  IS  DUB  ON  THE  LAST  DATE 
.  STAMPED  BELOW 


I0\i         5 

?cr  14 


131941VI 


\^\^ 


YC  20693 


161*55 


X 


